Simplify notmuch config docs

Author: lucc

docs/source/api/settings.rst

@@ -17,9 +17,10 @@ There are four types of user settings:
 |                                    | or as given by the `hooksfile`   |                                             |
 |                                    | config value                     |                                             |
 +------------------------------------+----------------------------------+---------------------------------------------+
-| notmuch config                     | :file:`~/.notmuch-config` or     | :meth:`SettingsManager.get_notmuch_setting` |
-|                                    | given by `$NOTMUCH_CONFIG` or    |                                             |
+| notmuch config                     | notmuch config file as           | :meth:`SettingsManager.get_notmuch_setting` |
 |                                    | given by command option `-n`     |                                             |
+|                                    | or its default location          |                                             |
+|                                    | described in `notmuch-config(1)` |                                             |
 +------------------------------------+----------------------------------+---------------------------------------------+
 | mailcap -- defines shellcommands   | :file:`~/.mailcap`               | :meth:`SettingsManager.mailcap_find_match`  |
 | to handle mime types               | (:file:`/etc/mailcap`)           |                                             |

docs/source/usage/cli_options.rst

@@ -2,8 +2,7 @@
 -c FILENAME, --config=FILENAME
                  configuration file (default: ~/.config/alot/config)
 -n FILENAME, --notmuch-config=FILENAME
-                 notmuch configuration file (default: $NOTMUCH_CONFIG
-                 or ~/.notmuch-config)
+                 notmuch configuration file (default: see notmuch-config(1))
 -C COLOURS, --colour-mode=COLOURS
                  number of colours to use on the terminal; must be 1, 16 or 256
                  (default: configuration option `colourmode` or 256)