Some tidyup of links and usage guide wording for docs site

[david-martin]

Part of #53
A docs site PR will follow to have sidenav links to the 3 pages added so they can be discovered more easily.

• Change links so they are less likely to be out of date
• Remove some redundant content
• Fixup start of lists for docs site formatting (see screenshot below of problem)
• Add link to usage guides from the HTTPRoute page to avoid duplicating usage guide content

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 0.38%. Comparing base (5ec96a0) to head (8e04933).

Additional details and impacted files

@@          Coverage Diff          @@
##            main     #60   +/-   ##
=====================================
  Coverage   0.38%   0.38%           
=====================================
  Files         17      17           
  Lines        783     783           
=====================================
  Hits           3       3           
  Misses       780     780           

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[jasonmadigan]

lgtm