docs: Updated docs to include information on easing functions

[chasec22]

closes #15992

This is a minor update to the easing documents. It adds an overview description for the module and short descriptions for each of the easing functions.

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[shivan-s]

@chasec22 awesome work. I've always had to guess what these do, and thanks to this PR, I don't need to guess no longer. Plus, I discovered some new easing functions haha.

Do you think the docs you added for each of the easing functions, you could also include as a sentence description on the docs?

CleanShot.2025-06-08.at.20.17.53.mp4