Improve Consul Health checks

[mcmikius]

update docs
add tests

[codecov]

Codecov Report

Attention: Patch coverage is 95.06173% with 8 lines in your changes are missing coverage. Please review.

Project coverage is 79.87%. Comparing base (6bbb770) to head (3902c55).
Report is 4 commits behind head on main.

Files	Patch %	Lines
...ts/HealthChecksTests/ConsulHealthChecksTests.swift	96.09%	5 Missing ⚠️
Tests/HealthChecksTests/Mocks/MockClient.swift	50.00%	3 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main      #16       +/-   ##
===========================================
+ Coverage   64.95%   79.87%   +14.92%     
===========================================
  Files          17       19        +2     
  Lines         505      631      +126     
===========================================
+ Hits          328      504      +176     
+ Misses        177      127       -50     

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