chore: keep old selfhost compose file (#9280)

.docker/selfhost/.env.example

@@ -0,0 +1,23 @@
+# select a revision to deploy, available values: stable, beta, canary
+AFFINE_REVISION=stable
+
+# set the port for the server container it will expose the server on
+PORT=3010
+
+# set the host for the server for outgoing links
+# AFFINE_SERVER_HTTPS=true
+# AFFINE_SERVER_HOST=affine.yourdomain.com
+# or 
+# AFFINE_SERVER_EXTERNAL_URL=https://affine.yourdomain.com
+
+# position of the database data to persist
+DB_DATA_LOCATION=~/.affine/self-host/postgres
+# position of the upload data(images, files, etc.) to persist
+UPLOAD_LOCATION=~/.affine/self-host/storage
+# position of the configuration files to persist
+CONFIG_LOCATION=~/.affine/self-host/config
+
+# database credentials
+DB_USERNAME=affine
+DB_PASSWORD=
+DB_DATABASE=affine