[PATCH] doc: Clean up warnings when building notmuch-emacs docs

[David Bremner]

Daniel Kahn Gillmor <dkg at fifthhorseman.net> writes:

> Without this change, we see this during the build:
>
>     sphinx-build -b html -d doc/_build/doctrees -q ./doc doc/_build/html
>     …/doc/notmuch-emacs.rst:67: WARNING: Unexpected indentation.
>     …/doc/notmuch-emacs.rst:165: WARNING: Unexpected indentation.
>     …/doc/notmuch-emacs.rst:306: WARNING: Unexpected indentation.

The info looked ok to me. Pushed to master.

d