update readme

Author: lopf

README.md

@@ -1,2 +1,20 @@
-# drupal-php
-Drupal PHP base image with some useful additions
+# Unic Drupal PHP Base
+
+Drupal PHP base image with some useful additions.
+
+## Versions
+
+| PHP | Branch | Notes |
+|---|---|---|
+| 7.4 | main | _EOL_ |
+| 8.1 | release/8.1 |   |
+| 8.2 |   | tbd |
+
+## Build
+### Local
+
+You can use your local Docker daemon to build the image. There are no depencencies:
+
+```bash
+docker build -t unicdocker/drupal-php:latest .
+```