README, docker-compose: work with local image (#5)

Author: srenatus

README.md

@@ -34,3 +34,9 @@ products by user.
   3. go to http://127.0.0.1:3000 (localhost yields CORS errors when reaching EOPA)
 * Open Dev Tools network tab for insights if something goes wrong: not all errors
   are currently surfaced in a usable way.
+* Since the backend functionality isn't in any EOPA edge build yet, run `make build-local`
+  on the propor EOPA source branch, and start the stack via
+
+  ```
+  EOPA_IMAGE=ko.local/enterprise-opa-private:edge EOPA_PULL_POLICY=missing docker compose up
+  ```

docker-compose.yaml

@@ -7,8 +7,8 @@ services:
       - eopa
 
   eopa:
-    image: ghcr.io/styrainc/enterprise-opa:edge
-    pull_policy: always # better when using :edge
+    image: ${EOPA_IMAGE:-ghcr.io/styrainc/enterprise-opa:edge}
+    pull_policy: ${EOPA_PULL_POLICY:-always}
     ports:
       - "8181:8181"
     command: