System information (version)

• OpenCV => 4.5

Detailed description

The documentation for color conversions does not explain what _FULL does, e.g. https://docs.opencv.org/4.5.0/d8/d01/group__imgproc__color__conversions.html#gga4e0972be5de079fed4e3a10e24ef5ef0ae0070d7e97f1e565cc0992d038e5498e
I believe this should be explained for each color conversion as there are different interpretations on forums.

Issue submission checklist

• [*] I report the issue, it's not a question
• [*] I checked the problem with documentation, FAQ, open issues,
  answers.opencv.org, Stack Overflow, etc and have not found solution
  There are some places with answers like:
  https://stackoverflow.com/questions/34200353/why-isnt-inrange-function-detecting-blue-color-when-i-have-given-it-the-entire
  or
  https://stackoverflow.com/questions/21782420/difference-between-hsv-and-hsv-full-in-opencv

but they actually give different answers (full gives H in [0,255] in one, [0,360] in the other).