text-quoting-style
The value of this user option is a symbol that specifies the style Emacs should use for single quotes in the wording of help and messages.
If the option’s value is curve, the style is ‘like this’ with curved single quotes.
If the value is straight, the style is ’like this’ with straight apostrophes.
If the value is grave, quotes are not translated and the style is ‘like this’ with grave accent and apostrophe, the standard style before Emacs version 25.
The default value nil acts like curve if curved single quotes seem to be displayable, and like grave otherwise.
Style to use for single quotes in help and messages. Its value should be a symbol.
It works by substituting certain single quotes for grave accent and apostrophe. This is done in help output (but not for display of Info manuals) and in functions like ‘message’ and ‘format-message’. It is not done in ‘format’.