Merge branch v2.2 into v2.3

docs/content/https/tls.md

@@ -428,6 +428,7 @@ metadata:
 
 spec:
   clientAuth:
+    # the CA certificate is extracted from key `tls.ca` of the given secrets.
     secretNames:
       - secretCA
     clientAuthType: RequireAndVerifyClientCert

docs/content/routing/providers/docker.md

@@ -535,7 +535,7 @@ You can declare UDP Routers and/or Services using labels.
          my-container:
            # ...
            labels:
-             - "traefik.udp.routers.my-router.entrypoint=udp"
+             - "traefik.udp.routers.my-router.entrypoints=udp"
              - "traefik.udp.services.my-service.loadbalancer.server.port=4123"
     ```