kconfig: fix trivial typos and update mconf documentation

This fixes lots of typos in comments and strings.

It also updates the documentation strings in mconf to reflect the changes in
the user interface from the two commits

6364fd0cb1e4c7f72b974613e0cf5744ae4d2cb2
  menuconfig: Add Save/Load buttons
1bdbac478a858d2aa73a6784c7c2e09de0f6d06b
  menuconfig: Get rid of the top-level entries for "Load an Alternate/Save an Alternate"

And it updates the layout of the example search result, i. e. moves down the
"Defined at" and "Depends on" lines and adds a symbol state ([=n]) to the
symbol in the "Selected by" line.

Furthermore, the help texts now should fit in 80 columns again when viewed
in mconf.

Signed-off-by: Martin Walch <walch.martin@web.de>
Reviewed-by: Jean Delvare <jdelvare@suse.de>
Reviewed-by: Wang YanQing <udknight@gmail.com>
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Christian Lamparter <chunkeey@googlemail.com>