feat: add .env.example for all

src/docker-registry/.env.example

@@ -0,0 +1,17 @@
+# Docker Registry Version
+REGISTRY_VERSION=3.0.0
+
+# Port to bind to on the host machine
+REGISTRY_PORT=5000
+
+# Authentication settings
+REGISTRY_AUTH=htpasswd
+REGISTRY_AUTH_HTPASSWD_REALM=Registry Realm
+REGISTRY_AUTH_HTPASSWD_PATH=/certs/passwd
+
+# TLS settings (optional)
+REGISTRY_HTTP_TLS_CERTIFICATE=
+REGISTRY_HTTP_TLS_KEY=
+
+# OpenTelemetry settings
+OTEL_TRACES_EXPORTER=none