Doc/git-submodule: improve readability and grammar of a sentence

While at it, correctly quote important words.

Signed-off-by: Kaartic Sivaraam <kaartic.sivaraam@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-submodule.txt

@@ -70,8 +70,8 @@ status [--cached] [--recursive] [--] [<path>...]::
 	Show the status of the submodules. This will print the SHA-1 of the
 	currently checked out commit for each submodule, along with the
 	submodule path and the output of 'git describe' for the
-	SHA-1. Each SHA-1 will be prefixed with `-` if the submodule is not
-	initialized, `+` if the currently checked out submodule commit
+	SHA-1. Each SHA-1 will possibly be prefixed with `-` if the submodule is
+	not initialized, `+` if the currently checked out submodule commit
 	does not match the SHA-1 found in the index of the containing
 	repository and `U` if the submodule has merge conflicts.
 +
@@ -132,15 +132,15 @@ expects by cloning missing submodules and updating the working tree of
 the submodules. The "updating" can be done in several ways depending
 on command line options and the value of `submodule.<name>.update`
 configuration variable. The command line option takes precedence over
-the configuration variable. if neither is given, a checkout is performed.
-update procedures supported both from the command line as well as setting
-`submodule.<name>.update`:
+the configuration variable. If neither is given, a 'checkout' is performed.
+The 'update' procedures supported both from the command line as well as
+through the `submodule.<name>.update` configuration are:
 
 	checkout;; the commit recorded in the superproject will be
 	    checked out in the submodule on a detached HEAD.
 +
 If `--force` is specified, the submodule will be checked out (using
-`git checkout --force` if appropriate), even if the commit specified
+`git checkout --force`), even if the commit specified
 in the index of the containing repository already matches the commit
 checked out in the submodule.
 
@@ -150,8 +150,8 @@ checked out in the submodule.
 	merge;; the commit recorded in the superproject will be merged
 	    into the current branch in the submodule.
 
-The following procedures are only available via the `submodule.<name>.update`
-configuration variable:
+The following 'update' procedures are only available via the
+`submodule.<name>.update` configuration variable:
 
 	custom command;; arbitrary shell command that takes a single
 	    argument (the sha1 of the commit recorded in the