Incorrect docblock for embed_defaults filter

[swissspidy]

The embed_defaults filter passes width and height in an array (using compact), and the url as a second param. The docblock lists three params though.

It should be made clear that only two paerams are passed to the filter callback.

[DrewAPicture]

In 35485:

Docs: Correctly notate that the default $width and $height embed dimensions are passed to the embed_defaults filter as a compacted array, and not two distinct parameters.

Props swissspidy.
Fixes #34522.