split out doc rules to a separate page
moved astropy.sphinx.ext docs to docs section
Minor text fixes
adjust edit_on_github docstring to be in line with other extension docs
automodsumm doc tweaks
Added blurb at beginning of docguide
typo fix in edit_on_github
various title wording and ordering tweaks in developer docs
Reorganized building/releasing into three sections
Title change for leading dev section in docs
moved vision from toc to inline reference
Improves the output formatting of units.  The old method always used scientific notation, so you'd get string things like `u.min` displaying as `6 * 10^1 s` rather than just `60 s`.  The new method just builds on Python's "general purpose" float format `g`.
Add a test
Typo fixes pointed out by @mdboom
Fixes suggested/inspired by @iguananaut
Update docs to reflect new formatting
Fix ordering of output from compose so it is ordered by abs(x.scale) (more meaningful than ordering by the string sort).
Fix LaTeX spacing of unit format output
Fix double space problem in default formatting
Update test for new LaTeX formatting