Merge from origin/emacs-26

6f495ab (origin/emacs-26) Another round of manual fixups
59344c4 * doc/lispref/customize.texi (Custom Themes): Clarify .el pre...
6386efc * doc/emacs/entering.texi (Entering Emacs): Another wording fix.
e21f018 * doc/lispref/functions.texi (Inline Functions): Fix typo (Bu...
1c2fb04 * lisp/imenu.el (imenu-generic-expression): Rephrase doc (Bug...
b90e91c Fix last change of @key markup
f180075 * doc/emacs/entering.texi (Entering Emacs): Fix markup.

diff --cc doc/emacs/dired.texi
Simple merge

diff --cc doc/lispref/functions.texi
Simple merge