glossary.rst: fix TODO comment markup

Commit b853ad906a2e0527e0313fb70d42137ae2d7aa11 added the sphinx
`glossary` directive, but it broke the TODO comments that were written
into the page. Indenting these multi-line comment blocks caused the
comment text after the first line of the block to bleed into the page.
Merge pull request #12 from larsbutler/fix-glossary-comments

glossary.rst: fix TODO comment markup which caused comments to show up in final page.