update documentation for post-update hook

hooks/post-update.sh

@@ -2,6 +2,12 @@
 # This script is copyright Oz N Tiram <nahumoz@gmail.com>
 # It is distributed under the terms of GPLv3
 
+# To use this hook rename it to post-update
+# Also you need the following software packages installed
+#
+#  * curl
+#  * openssl
+#
 # EDIT THE FOLLOWING VARIABLES TO FIT YOUR NEEDS
 # THE KEY SHOULD ALSO BE KNOWN ON THE SERVER THAT LISTENS TO SUBMITS
 SECRET_KEY=VERYSECRETLONGKEYYOUSHOULDDEFINITELYEDIT