Document the "email activation required" setting

gate-teamware/README.md

@@ -39,6 +39,7 @@ Things you will commonly need to override include:
     - `secret` - name of the secret holding the TLS certificate for the configured `hostName`.  Whether this is required or optional depends on the cluster and its configured ingress controller, e.g. the GATE cluster is set up to use a `*.gate.ac.uk` wildcard certificate for ingresses that do not specify their own, so on that cluster if the `hostName` matches that wildcard then a separate secret is not required.
   - `enabled` - using the ingress is the simplest way to expose the Teamware application correctly, but if you are unable to install an ingress controller in your cluster you can set this property to `false` and establish an alternative way to expose the Teamware services at the correct URLs - this could be a separate reverse proxy deployed manually into your cluster as a `LoadBalancer` service, or by making the `backend` and `staticFiles` services be type `NodePort` and replicating the ingress rules at an external gateway of some kind.  All requests to the `publicUrl` need to go to the backend service, _except_ those where the path prefix is `/static` which should go to the static service instead.
 - `email` settings to be able to send registration and password reminder emails
+  - `activationEnabled` (default `false`) - do we require new accounts to verify their email addresses before use by way of an emailed verification code?
   - `adminAddress` - email address of the administrator, used as the "from" address on generated emails
   - `backend` - "smtp" to send mail via an SMTP server, "gmail" to use the GMail API.
   - for the "smtp" backend: