Remove duplicate README.rst documentation and add links to ReadTheDocs documentation

[pmantica1]

In this diff, I remove all of the duplicate README.rst documentation and add links to ReadTheDocs.

Note:
We currently have a free ReadTheDocs account. If we ever decide to move to a ReadTheDocs business account then we will be given a different domain, (something like kensho-graphql-compiler.readthedocs.com). I already spoke with the ReadTheDocs support and they said that they can help us keep the current graphql-compiler.readthedocs.io domain as well if we make this transition. So the links I've included in this pr won't become invalid if we do decide to move to a business account.

Also, I did not really find much benefit to having a business account besides the ability to have one unique Kensho account for managing the ReadTheDocs websites of all the Kensho repositories. The compiler is currently the only Kensho repo that is integrated with ReadTheDocs though.

[codecov]

Codecov Report

Merging #918 into main will increase coverage by 0.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main     #918      +/-   ##
==========================================
+ Coverage   95.02%   95.04%   +0.01%     
==========================================
  Files         109      109              
  Lines        8732     8739       +7     
==========================================
+ Hits         8298     8306       +8     
+ Misses        434      433       -1     

Impacted Files	Coverage Δ
graphql_compiler/typedefs.py	100.00% <0.00%> (ø)
graphql_compiler/schema/__init__.py	100.00% <0.00%> (ø)
graphql_compiler/compiler/emit_sql.py	98.49% <0.00%> (ø)
graphql_compiler/compiler/metadata.py	99.13% <0.00%> (ø)
graphql_compiler/macros/validation.py	100.00% <0.00%> (ø)
graphql_compiler/compiler/validation.py	100.00% <0.00%> (ø)
graphql_compiler/compiler/expressions.py	92.07% <0.00%> (ø)
graphql_compiler/query_formatting/common.py	97.87% <0.00%> (ø)
graphql_compiler/cost_estimation/analysis.py	99.04% <0.00%> (ø)
graphql_compiler/query_pagination/__init__.py	100.00% <0.00%> (ø)
... and 13 more

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[obi1kenobi]

Would love @JulianGoetz and @branen's eyes on this.

[branen]

Nice work! I've suggested a few local edits; otherwise, it looks good.

[branen]

Looks good!