Help mode not working for \prime #22013
Description
The help mode that shows the latex hotkey for unicode character does not work for ′, possibly because it is not a valid variable name by itself.
help?> ′
ERROR: Invalid @var syntax `invalid character "′"`.
Kind of related but different. It might also be useful to have doc mode text for other special characters. Some, like ', can be ambiguous so probably both meanings should be mentioned.