Add Cloud Code guide to README

[dplewis]

Make the guide easily accessible.

Edit: I also want to test the benchmarked too :P, it should trigger when this is merged

[codecov]

Codecov Report

Merging #5936 into master will increase coverage by 0.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #5936      +/-   ##
==========================================
+ Coverage   93.64%   93.66%   +0.01%     
==========================================
  Files         156      156              
  Lines       10838    10838              
==========================================
+ Hits        10149    10151       +2     
+ Misses        689      687       -2

Impacted Files	Coverage Δ
...dapters/Storage/Postgres/PostgresStorageAdapter.js	96.6% <0%> (-0.09%)	⬇️
src/Adapters/Storage/Mongo/MongoStorageAdapter.js	92.94% <0%> (+0.7%)	⬆️

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