[easy] Fix readme.rst links to API/CLI examples

[chmreid]

Fix links to API/CLI examples in the Readme to point to the corresponding page in the readthedocs documentation, instead of pointing to the original .rst files

[codecov-io]

Codecov Report

Merging #503 into master will increase coverage by 0.7%.
The diff coverage is n/a.

@@            Coverage Diff            @@
##           master     #503     +/-   ##
=========================================
+ Coverage   85.67%   86.38%   +0.7%     
=========================================
  Files          42       42             
  Lines        1906     2012    +106     
=========================================
+ Hits         1633     1738    +105     
- Misses        273      274      +1

Impacted Files	Coverage Δ
hca/dss/__init__.py	92.35% <0%> (+1.94%)	⬆️

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