Fix documentation warnings

This doesn’t fix them all, but at least makes the build a bit more
readable.

doc/conf.py

@@ -59,7 +59,7 @@ master_doc = 'index'
 #
 # This is also used if you do content translation via gettext catalogs.
 # Usually you set "language" from the command line for these cases.
-language = None
+language = 'en'
 
 # List of patterns, relative to source directory, that match files and
 # directories to ignore when looking for source files.

doc/synopsis.rst

@@ -4,15 +4,15 @@ Synopsis
 biboumi [-ht] [*config_filename*]
 
 Command-Line Options
-========
+====================
 
 -h, \\-\\-help
-~~~~~~~~
+~~~~~~~~~~~~~~
 
 Display a help message and exit.
 
 -t, \\-\\-test-config
-~~~~~~~~
+~~~~~~~~~~~~~~~~~~~~~
 
 Do not run, just test the configuration file syntax. Exit with a 0
 status if the configuration is valid, exits with a non-zero status