[Cin] New image and explanation added to Manual ChromaKey(HSV)

Andrea has graciously added a new color wheel image + explanation to help precisely describe the image for Chroma Key HSV. It can be temporarily viewed since it is not part of the Manual yet by keying in: https://cinelerra-gg.org/download/CinelerraGG_Manual/Updated_Chroma_key_HSV.... and then scrolling down to "Usage". He has updated other useful information at the same time. The online Manual is ONLY UPDATED when there is a new binary release so that nothing new shows up in the Manual that is not in the AppImage / binary. (So that is why Compositor_Window.html and Compositor_window.html are still there, i.e. upper case and lower case -- this will be fixed upon the next binary/manual release).