bug#23071: 25.0.90; doc string of `global-eldoc-mode'

[Drew Adams]

This is surely incorrect, according to the code:

 "Enable 'eldoc-mode' in all buffers where it's applicable."

The command `global-eldoc-mode' is a toggle.  It does not _enable_
`eldoc-mode' in all "applicable" buffers; it toggles whether they are
enabled.

Also, the doc string should say what it means by "applicable" buffers
for Eldoc mode.  So far, the doc string is less than helpful - actually
harmful.


In GNU Emacs 25.0.90.3 (i686-w64-mingw32)
 of 2016-03-19
Windowing system distributor `Microsoft Corp.', version 6.1.7601
Configured using:
 `configure --host=i686-w64-mingw32 --without-dbus 'CFLAGS=-static
 -static-libgcc' LDFLAGS=-static-libgcc'