Update ReadTheDocs/Coveralls badges

[HunterMcGushion]

• ReadTheDocs badge now links to "stable" build, instead of "latest"
• Attempt to fix Coveralls badge stuck at old values

[codecov[bot]]

Codecov Report

Merging #160 into master will not change coverage. The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #160   +/-   ##
=======================================
  Coverage   93.72%   93.72%           
=======================================
  Files          46       46           
  Lines        4845     4845           
=======================================
  Hits         4541     4541           
  Misses        304      304

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Continue to review full report at Codecov.

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[coveralls]

Pull Request Test Coverage Report for Build 704

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 93.725%

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Totals
Change from base Build 698:	0.0%
Covered Lines:	4541
Relevant Lines:	4845

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💛 - Coveralls