Cleanup docs for route matching.

Documents:
  - mixing of named (token) matching and wildcard matching. Moved (and
    corrected) route chaining example. (Ref: #729)
  - megasplat (**) as part of wildcard matching (duplicate content from
    splat keyword).
  - Note support for named capture groups in section about regex routes.
reflect change
Merge branch 'docs/route_params_and_splats'