This is simpler and easier to explain, and should encourage better
typography. Do this in Electric Quote mode and when translating
quotes in docstrings. Inspired by a suggestion by Dmitry Gutov in:
https://lists.gnu.org/archive/html/emacs-devel/2015-08/msg00806.html
* doc/emacs/text.texi (Quotation Marks):
* doc/lispref/help.texi (Keys in Documentation):
* etc/NEWS:
Document this.
* lisp/electric.el (electric-quote-post-self-insert-function):
* src/doc.c (Fsubstitute_command_keys):
Always treat ' like ’ even when not matched by an open quote.