ipaclient_setup_nss: Documentation: Add default for selinux_works

The default value for selinux_works was missing in the DOCUMENTATION
section.

roles/ipaclient/library/ipaclient_setup_nss.py

@@ -156,6 +156,7 @@ options:
     description: True if selinux status check passed
     required: false
     type: bool
+    default: false
   krb_name:
     description: The krb5 config file name
     type: str