Update docker-in-gvisor.md

Author: thundergolfer

g3doc/user_guide/tutorials/docker-in-gvisor.md

@@ -8,7 +8,7 @@ network driver and the bridge network driver are tested and supported.
 
 ### NOTE on runsc setup
 
-To run docker within gvisor, runsc must be enable to to allow raw sockets. This
+To run docker within gvisor, runsc must be enabled to allow raw sockets. This
 is not the default, `--net-raw` must be passed to runsc. To use the following
 tutorial, that means having the following configuration in
 `/etc/docker/daemon.json`: