doc: remove synopsis

[avivkeller]

As titled. Re-open of #59216

cc previous approvers: @marco-ippolito @ovflowd

[richardlau]

Would URLs get redirected?
e.g.

• https://nodejs.org/docs/latest/api/synopsis.html
• https://nodejs.org/docs/latest-v24.x/api/synopsis.html

If not then I'd be inclined to not backport it to LTS releases.

[AugustinMauroy]

IMO synopsis is usefull. But we can discuss about merging index and documentation

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.30%. Comparing base (00f0f8c) to head (225a03f).
⚠️ Report is 4 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #65246      +/-   ##
==========================================
- Coverage   90.31%   90.30%   -0.02%     
==========================================
  Files         760      760              
  Lines      248637   248637              
  Branches    46942    46934       -8     
==========================================
- Hits       224556   224523      -33     
- Misses      15475    15515      +40     
+ Partials     8606     8599       -7     

see 28 files with indirect coverage changes

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[avivkeller]

@MikeMcC399 I linked the wrong PR, the correct one was #59216

@AugustinMauroy @MikeMcC399 to quote myself in that PR:

• The Usage section is essentially a less detailed version of what's already covered in cli.md#synopsis.
• The Example section closely mirrors the content in the official guide on getting started with Node.js.