Clearification of what an action actually is.

[takkun324]

There was no definition of an action itself. I also simplified the sentence, "An InputEvent may or may not represent a predefined action" to say that actions are not required but useful (combining with the next sentence).

Without the definition, I had thought actions were pre-defined input conditions (input states, rather than the input itself, since an action must have it's input defined). That mess of inquiry can be read here: https://www.reddit.com/r/godot/comments/xfvmg8/can_we_define_our_own_inputanalysis_for_inputmap/ Skip to first part of my last post to see the wording that corrected my understanding of what actions were.

This is my first-ever proposal. Thank you for the opportunity to contribute to the docs and help everyone understand things a little easier. -- Kevin