multisamples config variable missing documentation

[gabeklavans]

The entry at https://docs.panda3d.org/1.10/python/programming/configuration/list-of-all-config-variables for the multisamples config variable just states: "The minimum number of samples requested."

However, the real behavior is documented at https://github.com/panda3d/panda3d/blob/master/panda/src/display/config_display.cxx#L465, stating "The number of samples requested. Set this to 1 to request the maximum number of samples available"

There's also no mention of this at https://docs.panda3d.org/1.10/python/programming/render-attributes/antialiasing

I believe setting it to "1" to max it out is unintuitive enough that this should be included in the documentation somewhere.