Merge pull request #26 from continuousphp/feat/doc-postgres-import

adding import postgresql database documentation for client

Author: RSchumacher13

docs/databases/postgresql.md

@@ -38,4 +38,9 @@ Our containers implement the following PHP extensions for PostgreSQL :
   <tr>
     <td>Password</td><td>password</td>
   </tr>
-</table>
+</table>
+
+## Importing database dump
+
+ContinuousPHP provides users with the ability to import postgresql database dump files. To enable it, simply add an environment variable `PATH_IMPORT_DUMP_DB_POSTGRESQL` which refers to the absolute path of specified database dump file in repository context. 
+If you are using GitHub you should store it with [Git LFS](https://git-lfs.github.com/).