typo: it is worth noting. That is something (and not nothing). (#425)

security/trust/README.md

@@ -122,7 +122,7 @@ In this step you will enable Docker Content Trust, sign images as you push them,
 
    > **Note:** If you are using `sudo` with your Docker commands, you will need to preceded the above command so that it looks like this`sudo export DOCKER_CONTENT_TRUST=1`
 
-   It is worth nothing that although Docker Content Trust is now enabled, all Docker commands remain the same. Docker Content Trust will work silently in the background.
+   It is worth noting that although Docker Content Trust is now enabled, all Docker commands remain the same. Docker Content Trust will work silently in the background.
 
 2. Pull the `riyaz/dockercon:trust` signed image.