Access plotting help from plot context menu #3803
Description
Noted in #3793, point 9.
Is your feature request related to a problem? Please describe.
There is no Help option on a plot context menu.
So, if you want help on an a context menu option, most of which resides in graph_help.rst, the only option at present is to do Help > Documentation and use the search box.
Describe the solution you'd like
Add a Help option to the context menu.