User Guide Notebook for Azimuthal Mean

[philipc2]

If the preference is to add that later, could you please create an issue regarding that, if none exists. Also, who is going to write that guide, @jpan84 maybe you?

Originally posted by @erogluorhan in https://github.com/UXARRAY/uxarray/pull/1255#pullrequestreview-3225490866