Index entries for * and ** were added in #12531 so that both are indexed as operators, in function definitions, in function calls, and in the tutorial. If any of these places need improvement, there should be specific suggestions.

I do not think there should be separate documentation for the * symbol. It would only duplicate what is already present. There are many symbols with multiple uses.

Changing html search search for symbols, if possible, would be a different issue. But returning every use of '*' in the docs would not seem too useful. For anything in the index, the index in more useful.