fix readthedocs.io build process

docs/index.md

@@ -0,0 +1 @@
+{!README.md!}

docs/requirements.txt

@@ -0,0 +1,2 @@
+mkdocs==1.1
+markdown-include==0.5.1

mkdocs.yml

@@ -10,6 +10,7 @@ extra_css:
     - assets/highlight.css
 markdown_extensions:
   - admonition
+  - markdown_include.include
 repo_url: https://github.com/jrnl-org/jrnl/
 site_author: Manuel Ebert
 site_description: Collect your thoughts and notes without leaving the command line.

readthedocs.yml

@@ -0,0 +1,22 @@
+# readthedocs.yml
+# Read the Docs configuration file
+# See https://docs.readthedocs.io/en/stable/config-file/v2.html for details
+
+# Required
+version: 2
+
+# Build documentation in the docs/ directory
+mkdocs:
+  configuration: mkdocs.yml
+  fail_on_warning: false
+
+# Optionally build your docs in additional formats such as PDF
+formats:
+  - pdf
+  - epub
+
+# Optionally set the version of Python and requirements required to build your docs
+python:
+  version: 3.7
+  install:
+    - requirements: docs/requirements.txt