qerror: Add a user string for QERR_FEATURE_DISABLED

Missing from commit 821601ea5b.

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>

qerror.c

@@ -116,6 +116,10 @@ static const QErrorStringTable qerror_table[] = {
         .error_fmt = QERR_FD_NOT_SUPPLIED,
         .desc      = "No file descriptor supplied via SCM_RIGHTS",
     },
+    {
+        .error_fmt = QERR_FEATURE_DISABLED,
+        .desc      = "The feature '%(name)' is not enabled",
+    },
     {
         .error_fmt = QERR_INVALID_BLOCK_FORMAT,
         .desc      = "Invalid block format '%(name)'",