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

6364fd0cb1
  menuconfig: Add Save/Load buttons
1bdbac478a
  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>

scripts/kconfig/symbol.c

@@ -1047,7 +1047,7 @@ sym_re_search_free:
  * When we check for recursive dependencies we use a stack to save
  * current state so we can print out relevant info to user.
  * The entries are located on the call stack so no need to free memory.
- * Note inser() remove() must always match to properly clear the stack.
+ * Note insert() remove() must always match to properly clear the stack.
  */
 static struct dep_stack {
 	struct dep_stack *prev, *next;