Add notes about the docker-compose usage

Change-Id: I73c8467ab58caf2082740e682c9175f3eb494a14

Author: dotWee

README.md

@@ -35,7 +35,26 @@ Steps for 1):
 
 Steps for 2):
 
-- run the Docker container: `docker run -p 8080:80 awesometechnologies/synapse-admin`
+- run the Docker container from the public docker registry: `docker run -p 8080:80 awesometechnologies/synapse-admin` or use the (docker-compose.yml)[docker-compose.yml]: `docker-compose up -d`
+
+  > note: if you're building on an architecture other than amd64 (for example a raspberry pi), make sure to define a maximum ram for node. otherwise the build will fail.
+
+  ```yml
+  version: "3"
+
+  services:
+    synapse-admin:
+      container_name: synapse-admin
+      hostname: synapse-admin
+      build:
+        context: https://github.com/Awesome-Technologies/synapse-admin.git
+        # args:
+        #   - NODE_OPTIONS="--max_old_space_size=1024"
+      ports:
+        - "8080:80"
+      restart: unless-stopped
+  ```
+
 - browse to http://localhost:8080
 
 ## Screenshots