Float '[source]' links right.
Make admonition blocks visible.
Tighten up 'note' sections (drop extra graph).
Remove 'docstring poetry'.

Wrap prose docstring paragraphs at 72 characters.
Remove spurious 'bulk_mutation' argument in docstring example.

Fixes #408.
Merge pull request #413 from tseaver/remove-docstring-poetry

Remove docstring poetry