Docs: Bugpoint fixups from JF

Also dropping the `autosectionlabel_maxdepth = 1` so that I can actually use the auto section labels.
Adds warning on bash substitution on scripting intro page when talking about `yosys -p`.

docs/source/conf.py

@@ -64,7 +64,6 @@ if os.getenv("READTHEDOCS"):
 
 # Ensure that autosectionlabel will produce unique names
 autosectionlabel_prefix_document = True
-autosectionlabel_maxdepth = 1
 
 # include todos for previews
 extensions.append('sphinx.ext.todo')