Clarify documentation examples of Route methods

[andrew-werdna]

Fixes #666

Summary of Changes

1. Update Route method documentation comments where the example in the comments showed a Router before. Updated method names include:
   • Headers
   • HeadersRegexp
   • Host
   • Path
   • Queries
   • Subrouter
   • URL

Notes:

• This includes what PR #667 did plus some changes requested by a maintainer in the comments
• I was a little torn about changing the example in Subrouter since (*Router).Host() (like several (*Router) methods) just calls (*Router).NewRoute().Host() so I understand if maintainers are ambivalent about that example or want it to remain the same.

[andrew-werdna]

@james-d-elliot you just approved PR #667, what do you think of this one?

[coreydaley]

@apoorvajagtap ptal

[codecov[bot]]

Codecov Report

Merging #672 (d94561d) into main (24c3e7f) will not change coverage. The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #672   +/-   ##
=======================================
  Coverage   78.44%   78.44%           
=======================================
  Files           5        5           
  Lines         877      877           
=======================================
  Hits          688      688           
  Misses        135      135           
  Partials       54       54           

Files Changed	Coverage Δ
route.go	69.29% <ø> (ø)