timers: document ref option for scheduler.wait

[ShogunPanda]

Follow-up of #54404. See: https://github.com/nodejs/node/pull/54404#discussion_r1730292452 and https://github.com/nodejs/node/pull/54404#discussion_r1730293843

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 87.34%. Comparing base (0b3ae01) to head (c875a81). Report is 49 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #54605      +/-   ##
==========================================
+ Coverage   87.32%   87.34%   +0.01%     
==========================================
  Files         649      649              
  Lines      182570   182566       -4     
  Branches    35026    35030       +4     
==========================================
+ Hits       159432   159456      +24     
+ Misses      16406    16389      -17     
+ Partials     6732     6721      -11     

Files with missing lines	Coverage Δ
lib/timers/promises.js	98.31% <100.00%> (-0.03%)	:arrow_down:

... and 24 files with indirect coverage changes

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/61686/

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/61693/

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/61696/

[nodejs-github-bot]

Landed in 294ae14b98fdd4696659169b63c6b871c6c71fa3