Merge from origin/emacs-26

818a68b * etc/HISTORY: Update for Emacs 26.2 release.
e04aa5a ; ChangeLog.3 update
8297e97 * etc/AUTHORS: Update.
8582936 Improve documentation of 'read-command'
dc81c05 ; * CONTRIBUTE: Mention where to ask for the copyright assign...
b77723a Fix an outdated URL in a comment

diff --cc CONTRIBUTE
Simple merge

diff --cc ChangeLog.3
Simple merge

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

diff --cc src/emacs.c
Simple merge

diff --cc src/minibuf.c
Simple merge