changed README

Initial documentation.

README.md

@@ -1,4 +1,28 @@
-# postgresql_passchanger_function
+# PostgreSQL expiration date management functions
+
+## Description
+
+This project tries to find a way to allow users the management of the `VALID UNTIL` expiration clause by themself.
+All without granting `super` permissions and having a histoc of changes on a _pseudo-audit_ table
+
+## Instructions
+
+### First deploy
+Deploy `passchanger.sql` on the desired cluster/database.
+
+It will:
+  * create a `dba` schema
+  * create a `dba` role
+  * Grant the minimum permissions for this new role so the whole thing works
+  * Create the 2 needed functions and grant permissions on them to `dba`
+
+
+### Allowing users to use that functions
+Take the file `grants_to_grant.sql` and modify the username _dodger_ so it match the username that should have the permissions.
+Execute the grants on the cluster/database you have deployed `passchanger.sql`
+
+
+### Changint password & extending expiration date
+
 
-Have a look at the comments