doc: extract lockfile doc from "manage dependencies" doc

[frostming]

Signed-off-by: Frost Ming me@frostming.com

Pull Request Checklist

• A news fragment is added in news/ describing what is new.
• Test cases added for changed code.

Describe what you have changed in this PR.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 85.07%. Comparing base (cfe036c) to head (679aa27).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2725   +/-   ##
=======================================
  Coverage   85.07%   85.07%           
=======================================
  Files         106      106           
  Lines       10539    10539           
  Branches     2288     2288           
=======================================
  Hits         8966     8966           
  Misses       1101     1101           
  Partials      472      472           

Flag	Coverage Δ
unittests	84.85% <ø> (ø)

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