Added --help flags to update and update_sub

So that developers will know what these commands do and how to use them.

Signed-off-by: Parker, Matt <mparker@pivotallabs.com>

update

@@ -1,4 +1,14 @@
-#!/bin/bash -x
+#!/bin/bash
+
+if [ "$1" == "--help" ]; then
+  echo "USAGE: $0"
+  echo "    This command takes no arguments."
+  echo ""
+  echo "This script does a git submodule update on all submodules"
+  exit 0
+fi
+
+set -x
 
 if [[ "$(git --version | grep 'version 1.7')x" != "x" ]]; then
   git pull && git submodule foreach --recursive git submodule sync && git submodule update --init --recursive

update_sub

@@ -1,5 +1,13 @@
 #!/bin/sh
 
+if [ "$1" == "--help" ]; then
+  echo "Usage: $0 REPO_NAME"
+  echo ""
+  echo "This script updates the requested submodule to the latest commit on origin."
+  echo "It will then prepare a commit message for you containing all of the commit messages between the previous submodule sha and the new submodule sha."
+  exit 0
+fi
+
 if [ "$#" -ne 1 ]; then
   echo "Usage: $0 REPO_NAME"
   exit 1