Remove @key{} markups from @kindex entries in manuals

Remove @key{} markups from @kindex entries in manuals

* doc/emacs/basic.texi:
* doc/emacs/buffers.texi:
* doc/emacs/building.texi:
* doc/emacs/calendar.texi:
* doc/emacs/custom.texi:
* doc/emacs/dired.texi:
* doc/emacs/display.texi:
* doc/emacs/files.texi:
* doc/emacs/frames.texi:
* doc/emacs/help.texi:
* doc/emacs/indent.texi:
* doc/emacs/killing.texi:
* doc/emacs/kmacro.texi:
* doc/emacs/mark.texi:
* doc/emacs/mini.texi:
* doc/emacs/misc.texi:
* doc/emacs/modes.texi:
* doc/emacs/msdos-xtra.texi:
* doc/emacs/msdos.texi:
* doc/emacs/mule.texi:
* doc/emacs/picture-xtra.texi:
* doc/emacs/programs.texi:
* doc/emacs/regs.texi:
* doc/emacs/rmail.texi:
* doc/emacs/screen.texi:
* doc/emacs/search.texi:
* doc/emacs/sending.texi:
* doc/emacs/text.texi:
* doc/emacs/trouble.texi:
* doc/misc/calc.texi:
* doc/misc/cc-mode.texi:
* doc/misc/ediff.texi:
* doc/misc/ert.texi:
* doc/misc/eww.texi:
* doc/misc/forms.texi:
* doc/misc/gnus.texi:
* doc/misc/idlwave.texi:
* doc/misc/info.texi:
* doc/misc/message.texi:
* doc/misc/mh-e.texi:
* doc/misc/newsticker.texi:
* doc/misc/org.texi:
* doc/misc/pcl-cvs.texi:
* doc/misc/rcirc.texi:
* doc/misc/reftex.texi:
* doc/misc/sc.texi:
* doc/misc/sieve.texi:
* doc/misc/vhdl-mode.texi:
* doc/misc/vip.texi:
* doc/misc/viper.texi:
* doc/misc/woman.texi: Remove @key{} markups from @kindex entries.