Reorganize reliability factors documentation

[AndrewSazonov]

Move “Reliability Factors” to the top level of the User Guide navigation, immediately after “Analysis Workflow”.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.39%. Comparing base (c448b70) to head (1bb1de8).
⚠️ Report is 1 commits behind head on develop.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop     #225   +/-   ##
========================================
  Coverage    90.39%   90.39%           
========================================
  Files          284      284           
  Lines        24789    24789           
  Branches      2909     2909           
========================================
  Hits         22409    22409           
  Misses        1754     1754           
  Partials       626      626           

Flag	Coverage Δ
unittests	90.39% <ø> (ø)

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