doc: Improve documentation in various places

* don't duplicate information between .rst files and docstrings
* if there's more than a trivial single-line documentation, put it as
  docstring into the python source and use ".. argparse" to pul it into
  the manual
* add documentation for some commands for which it was missing
* show one level deeper in the navigation table, listing the commands

Change-Id: Ib88bb7d12faaac7d149ee1f6379bc128b83bbdd5
diff --git a/docs/conf.py b/docs/conf.py
index a96b87e..6fea583 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -18,7 +18,7 @@
 # -- Project information -----------------------------------------------------
 
 project = 'osmopysim-usermanual'
-copyright = '2009-2021 by Sylvain Munaut, Harald Welte, Philipp Maier, Supreeth Herle'
+copyright = '2009-2022 by Sylvain Munaut, Harald Welte, Philipp Maier, Supreeth Herle'
 author = 'Sylvain Munaut, Harald Welte, Philipp Maier, Supreeth Herle'