docs: add nginx example (#1329)

* docs: add nginx example

Co-authored-by: bobby <1544881+desimone@users.noreply.github.com>

examples/nginx/docker-compose.yaml

@@ -0,0 +1,24 @@
+version: "3"
+services:
+  nginx:
+    image: nginx
+    restart: unless-stopped
+    ports:
+      - "80:80"
+      - "443:443"
+    volumes:
+      - ./httpbin.conf:/etc/nginx/conf.d/httpbin.conf
+      - ./pomerium.conf:/etc/nginx/conf.d/pomerium.conf
+      - ./_wildcard.localhost.pomerium.io.pem:/etc/nginx/nginx.pem
+      - ./_wildcard.localhost.pomerium.io-key.pem:/etc/nginx/nginx-key.pem
+
+  httpbin:
+    image: kennethreitz/httpbin:latest
+    expose:
+      - 80
+  pomerium:
+    image: pomerium/pomerium:latest
+    volumes:
+      - ./config.yaml:/pomerium/config.yaml:ro
+    expose:
+      - 80