[PSR-5] Please clarify that @method can be used for non-magic usages

[Gabriel O]

I had a problem with this in the past in https://github.com/vimeo/psalm/issues/632

Usage of this annotation is nowadays pretty wide spread, but they are often not only used in classes with __call, but also just for specifying what inherited methods return, in covariant style.

Such usages are currently controversial, since @method is defined only in https://docs.phpdoc.org/references/phpdoc/tags/method.html which strongly hints this is only for situations when you want to describe __call methods.

Please think about this in PSR-5 as well.