Recent Commits to styleguide:gh-pages

Update C++ style guide (#937)

- Allow coroutine use via libraries approved by project leads
- Disallow using a space before `*` and `&` for pointer and reference
  types
- Simplify guidance for using vertical whitespace
- Other minor formatting / typography / wording fixes, e.g. adding
  goodcode/badcode annotations to examples

Add styling rules for good code examples in shared stylesheet

This change primarily affects the C++ style guide: while a number of
other style guides also use <pre> directly for code examples, the other
style guides all use JS to prettyprint the code blocks, and the
prettyprinter overrides the styles specified in the shared stylesheet.

The exception is the AngularJS style guide, but it is already
inconsistently formatted and this change does not make it any worse.

There are also several other style guides other than C++ where
good/neutral are rendered identically; this commit does not attempt to
address those either.