kbuild: clarify the creation of the LOCALVERSION_AUTO string.

Clarify the creation of the LOCALVERSION_AUTO string during kernel
configuration, and fix a couple typoes while we're there.
Signed-off-by: NRobert P. J. Day <rpjday@mindspring.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NSam Ravnborg <sam@ravnborg.org>

init/Kconfig

@@ -80,16 +80,20 @@ config LOCALVERSION_AUTO
 	default y
 	help
 	  This will try to automatically determine if the current tree is a
-	  release tree by looking for git tags that
-	  belong to the current top of tree revision.
+	  release tree by looking for git tags that belong to the current
+	  top of tree revision.
 
 	  A string of the format -gxxxxxxxx will be added to the localversion
-	  if a git based tree is found.  The string generated by this will be
+	  if a git-based tree is found.  The string generated by this will be
 	  appended after any matching localversion* files, and after the value
-	  set in CONFIG_LOCALVERSION
+	  set in CONFIG_LOCALVERSION.
 
-	  Note: This requires Perl, and a git repository, but not necessarily
-	  the git or cogito tools to be installed.
+	  (The actual string used here is the first eight characters produced
+	  by running the command:
+
+	    $ git rev-parse --verify HEAD
+
+	  which is done within the script "scripts/setlocalversion".)
 
 config SWAP
 	bool "Support for paging of anonymous memory (swap)"