kconfig: doc: fix a typo in the note about 'imply'

This sentence does not make sense due to a typo. Fix it.

Fixes: def2fbff ("kconfig: allow symbols implied by y to become m")
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>

Documentation/kbuild/kconfig-language.rst

@@ -184,7 +184,7 @@ applicable everywhere (see syntax).
   ability to hook into a secondary subsystem while allowing the user to
   configure that subsystem out without also having to unset these drivers.
 
-  Note: If the combination of FOO=y and BAR=m causes a link error,
+  Note: If the combination of FOO=y and BAZ=m causes a link error,
   you can guard the function call with IS_REACHABLE()::
 
 	foo_init()