Update URL and host config for local kubernetes cluster

[jmgrady]

Update the instructions for setting up The Combine on a local Kubernetes cluster in README.md. Specifically:

1. Changed the URL for The Combine from https://thecombine.local to https://thecombine.localhost. This URL change was made sometime ago since Google Chrome, Chromium Derivatives, and Firefox automatically map *.localhost to 127.0.0.1.
2. Removed instructions for updating the host machine's host configuration file.

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This change is 

[codecov-commenter]

Codecov Report

Patch coverage has no change and project coverage change: -14.41 ⚠️

Comparison is base (4202d78) 73.23% compared to head (f1e5486) 58.82%.

Additional details and impacted files

@@             Coverage Diff             @@
##           master    #2271       +/-   ##
===========================================
- Coverage   73.23%   58.82%   -14.41%     
===========================================
  Files          42      235      +193     
  Lines        3923     7767     +3844     
  Branches        0      502      +502     
===========================================
+ Hits         2873     4569     +1696     
- Misses       1050     2827     +1777     
- Partials        0      371      +371     

Flag	Coverage Δ
backend	73.23% <ø> (ø)
frontend	44.12% <ø> (?)

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see 193 files with indirect coverage changes

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[imnasnainaec]

Reviewed 1 of 1 files at r1, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @jmgrady)