github: add config templates + docs

- ghexport: use export_path (export_dir is still supported)

my/twitter/archive.py

@@ -18,9 +18,8 @@ except ImportError as e:
 
 
 from dataclasses import dataclass
-from ..core.common import Paths
+from ..core import Paths
 
-# TODO perhaps rename to twitter_archive? dunno
 @dataclass
 class twitter_archive(user_config):
     export_path: Paths # path[s]/glob to the twitter archive takeout

my/twitter/twint.py

@@ -14,6 +14,7 @@ from my.config import twint as user_config
 class twint(user_config):
     export_path: Paths # path[s]/glob to the twint Sqlite database
 
+####
 
 from ..core.cfg import make_config
 config = make_config(twint)