Update README, add Send base URL

README.md

@@ -1,4 +1,14 @@
 # Firefox Send in Docker compose
+This repository provides a basic Docker compose configuration to host a public
+[Firefox Send](https://github.com/mozilla/send) instance on your own domain.
+
+- Hosts on your own domain
+- Provides automatic SSL certificates through LetsEncrypt
+
+This configuration exposes a reverse proxy on ports 80 and 443, so these must be
+available.
+
+See [docker-compose.yaml](./docker-compose.yaml).
 
 ### Usage
 - Install Docker with Docker compose
@@ -12,6 +22,9 @@
 # Host to expose Send on
 HOST=send.example.org
 
+# Base URL for Send
+SEND_BASE_URL=https://send.example.org
+
 # Optional: for LetsEncrypt SSL, same as HOST
 LETSENCRYPT_HOST=