Remove ManSection labels in manual

[stertooy]

In both cases, GAPDoc automatically defines the exact same labels for the functions inside the ManSections, which causes a duplicate label warning/error.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.85%. Comparing base (64d9118) to head (d78a355).
⚠️ Report is 2 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master      #16   +/-   ##
=======================================
  Coverage   93.85%   93.85%           
=======================================
  Files           3        3           
  Lines         293      293           
=======================================
  Hits          275      275           
  Misses         18       18           

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.