Update diagrams-manual.rst

some typos, more to come probably
Update diagrams-manual.rst

another typo
Update diagrams-manual.rst

another one
Stylistic change ($) -> (#)

not sure whether this is a good idea,
so I left the two other occurrences
involving `pad .. $ ..` alone
Merge pull request #29 from ggreif/patch-1

Mostly typos