Fix typo in LightningModule.configure_callbacks() document

[hankyul2]

• Fix typo in LightningModule.configure_callbacks()

What does this PR do?

Fix typo in LightningModule.configure_callbacks() document (document link)

Change is monitor"val_acc" -> monitor="val_acc" (insert = statement)

This seems to so small typo, so I did not make any issue.

Does your PR introduce any breaking changes? If yes, please list them.

Nope

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Did you have fun?

Of course, I do 😁

[codecov]

Codecov Report

Merging #9591 (cfdee80) into master (f5608e9) will decrease coverage by 4%.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master   #9591    +/-   ##
=======================================
- Coverage      93%     89%    -4%     
=======================================
  Files         181     181            
  Lines       15349   15349            
=======================================
- Hits        14246   13630   -616     
- Misses       1103    1719   +616