Add reference documentation to docs site and separate out "Tips and Tricks" and "External Editors" from "Recipes" (#1332)

* First draft of command line reference, mostly pulled from help screen

* Add first draft of config file reference, mostly pulled from advanced.md

* Clean up config file doc for readability

* Add --config-file and remove examples from CLI reference

* Add warning about time zone in timeformat

* More small changes, and adding template config keyword

* Cleaning up and re-ordering config file reference

* Clean up reference and anything else from advanced documentation that can live elsewhere and linking to config file reference wherever config file is mentioned

* Fix syntax highlighting in command line reference, clean up content a bit, include --diagnostic

* Mention version config key

* Apply minor changes suggested in PR review

* Rename "recipes" to "Tips and Tricks", pull "External Editors" out of it into its own page, and redirect old recipes link to tips-and-tricks

* Revert broken mkdocs-redirects usage from last commit

docs/tips-and-tricks.md

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+<!-- Copyright (C) 2012-2021 jrnl contributors
+     License: https://www.gnu.org/licenses/gpl-3.0.html -->
+# Tips and Tricks
+
+This page contains tips and tricks for using `jrnl`, often in conjunction
+with other tools, including external editors.
+
+## Co-occurrence of tags
+
+If I want to find out how often I mentioned my flatmates Alberto and
+Melo in the same entry, I run
+
+```sh
+jrnl @alberto --tags | grep @melo
+```
+
+And will get something like `@melo: 9`, meaning there are 9 entries
+where both `@alberto` and `@melo` are tagged. How does this work? First,
+`jrnl @alberto` will filter the journal to only entries containing the
+tag `@alberto`, and then the `--tags` option will print out how often
+each tag occurred in this filtered journal. Finally, we pipe this to
+`grep` which will only display the line containing `@melo`.
+
+## Combining filters
+
+You can do things like
+
+```sh
+jrnl @fixed -starred -n 10 -to "jan 2013" --short
+```
+
+To get a short summary of the 10 most recent, favourite entries before
+January 1, 2013 that are tagged with `@fixed`.
+
+## Statistics
+
+How much did I write last year?
+
+```sh
+jrnl -from "jan 1 2013" -to "dec 31 2013" | wc -w
+```
+
+Will give you the number of words you wrote in 2013. How long is my
+average entry?
+
+```sh
+expr $(jrnl --export text | wc -w) / $(jrnl --short | wc -l)
+```
+
+This will first get the total number of words in the journal and divide
+it by the number of entries (this works because `jrnl --short` will
+print exactly one line per entry).
+
+## Importing older files
+
+If you want to import a file as an entry to `jrnl`, you can just do `jrnl < entry.ext`. But what if you want the modification date of the file to
+be the date of the entry in `jrnl`? Try this
+
+```sh
+echo `stat -f %Sm -t '%d %b %Y at %H:%M: ' entry.txt` `cat entry.txt` | jrnl
+```
+
+The first part will format the modification date of `entry.txt`, and
+then combine it with the contents of the file before piping it to jrnl.
+If you do that often, consider creating a function in your `.bashrc` or
+`.bash_profile`
+
+```sh
+jrnlimport () {
+  echo `stat -f %Sm -t '%d %b %Y at %H:%M: ' $1` `cat $1` | jrnl
+}
+```
+
+## Using templates
+
+!!! note
+    Templates require an [external editor](./advanced.md) be configured.
+
+A template is a code snippet that makes it easier to use repeated text
+each time a new journal entry is started. There are two ways you can utilize
+templates in your entries.
+
+### 1. Command line arguments
+
+If you had a `template.txt` file with the following contents:
+
+```sh
+My Personal Journal
+Title:
+
+Body:
+```
+
+The `template.txt` file could be used to create a new entry with these
+command line arguments:
+
+```sh
+jrnl < template.txt     # Imports template.txt as the most recent entry
+jrnl -1 --edit          # Opens the most recent entry in the editor
+```
+
+### 2. Include the template file in `jrnl.yaml`
+
+A more efficient way to work with a template file is to declare the file
+in your [config file](./reference-config-file.md) by changing the `template`
+setting from `false` to the template file's path in double quotes:
+
+```sh
+...
+template: "/path/to/template.txt"
+...
+```
+
+Changes can be saved as you continue writing the journal entry and will be
+logged as a new entry in the journal you specified in the original argument.
+
+!!! tip
+    To read your journal entry or to verify the entry saved, you can use this
+    command: `jrnl -n 1` (Check out [Formats](./formats.md) for more options).
+
+```sh
+jrnl -n 1
+```
+
+## Prompts on shell reload
+
+If you'd like to be prompted each time you refresh your shell, you can include
+this in your `.bash_profile`:
+
+```sh
+function log_question()
+{
+   echo $1
+   read
+   jrnl today: ${1}. $REPLY
+}
+log_question 'What did I achieve today?'
+log_question 'What did I make progress with?'
+```
+
+Whenever your shell is reloaded, you will be prompted to answer each of the
+questions in the example above. Each answer will be logged as a separate
+journal entry at the `default_hour` and `default_minute` listed in your
+`jrnl.yaml` [config file](../advanced/#configuration-file).
+
+## Display random entry
+
+You can use this to select one title at random and then display the whole
+entry. The invocation of `cut` needs to match the format of the timestamp.
+For timestamps that have a space between data and time components, select
+fields 1 and 2 as shown. For timestamps that have no whitespace, select
+only field 1.
+
+```sh
+jrnl -on "$(jrnl --short | shuf -n 1 | cut -d' ' -f1,2)"
+```
+
+
+## Launch a terminal for rapid logging
+You can use this to launch a terminal that is the `jrnl` stdin prompt so you can start typing away immediately.
+
+```bash
+jrnl --config-override editor ""
+```
+
+Bind this to a keyboard shortcut.
+
+Map `Super+Alt+J` to launch the terminal with `jrnl` prompt
+
+- **xbindkeys**
+In your `.xbindkeysrc`
+
+```ini
+Mod4+Mod1+j
+ alacritty -t floating-jrnl -e jrnl --config-override editor "",
+```
+
+- **I3 WM** Launch a floating terminal with the `jrnl` prompt
+
+```ini
+bindsym Mod4+Mod1+j exec --no-startup-id alacritty -t floating-jrnl -e jrnl --config-override editor ""
+for_window[title="floating *"] floating enable
+```
+## Visualize Formatted Markdown in the CLI
+
+Out of the box, `jrnl` can output journal entries in Markdown. To visualize it, you can pipe to [mdless](https://github.com/ttscoff/mdless), which is a [less](https://en.wikipedia.org/wiki/Less_(Unix))-like tool that allows you to visualize your Markdown text with formatting and syntax highlighting from the CLI. You can use this in any shell that supports piping.
+
+The simplest way to visualize your Markdown output with `mdless` is as follows:
+```sh
+jrnl --export md | mdless
+```
+
+This will render your Markdown output in the whole screen.
+
+Fortunately, `mdless` has an option that allows you to adjust the screen width by using the `-w` option as follows:
+
+```sh
+jrnl --export md | mdless -w 70
+```
+
+If you want Markdown to be your default display format, you can define this in your config file as follows:
+
+```yaml
+display_format: md
+# or
+display_format: markdown
+```
+
+For more information on how `jrnl` outputs your entries in Markdown, please visit the [Formats](./formats.md) section.
+