Merge from origin/emacs-27

Merge from origin/emacs-27

c04b92104c Add commentary in gtkutil.c
6290850dac Consistently stylize eldoc as ElDoc in prose
136e931189 Improve documentation of "C-u C-x ="
1f52771fd3 Mention floating rounding issues
c892ae65b4 Repair global-auto-revert-ignore-modes (bug#42271)
3a446a02fb ; * src/xdisp.c (decode_mode_spec): Fix commentary.
79f381b4a6 One more improvement of left/right-fringe display spec docs
1279bdb072 Another clarification of left/right-fringe display spec

# Conflicts:
#	doc/emacs/programs.texi