update readme

README.md

@@ -47,3 +47,30 @@ docker compose up -d --build
 ```
 
 The included compose file binds the app to `127.0.0.1:18080` on the host so a reverse proxy can publish it without exposing the Node container directly.
+
+### Production Build Note
+
+On the production host used for this project, npm registry downloads from inside Docker timed out unless `registry.npmjs.org` was pinned to a known-good IPv4 address during build. The proven build command is:
+
+```sh
+sudo docker build \
+  --network=host \
+  --add-host registry.npmjs.org:104.16.1.34 \
+  -t meme-protocol:latest .
+```
+
+Then start with the already-built image:
+
+```sh
+sudo docker compose up -d --no-build
+```
+
+If the registry IP ever stops working, resolve and test another IPv4 address for `registry.npmjs.org`, then replace `104.16.1.34` in the build command.
+
+When using a host-mounted data directory, the container writes as UID/GID `10001:10001`:
+
+```sh
+sudo mkdir -p ./data
+sudo chown -R 10001:10001 ./data
+sudo chmod -R u+rwX,g+rwX,o-rwx ./data
+```