BUG/MINOR: cli: "agent" was missing from the "enable"/"disable" help message

Commit 671b6f0 ("MEDIUM: Add enable and disable agent unix socket commands")
forgot to update the relevant help messages. This was done in 1.5-dev20, no
backport is needed.
diff --git a/src/dumpstats.c b/src/dumpstats.c
index 02bff56..63a615a 100644
--- a/src/dumpstats.c
+++ b/src/dumpstats.c
@@ -1828,7 +1828,7 @@
 			return 1;
 		}
 		else { /* unknown "enable" parameter */
-			appctx->ctx.cli.msg = "'enable' only supports 'frontend' and 'server'.\n";
+			appctx->ctx.cli.msg = "'enable' only supports 'agent', 'frontend' and 'server'.\n";
 			appctx->st0 = STAT_CLI_PRINT;
 			return 1;
 		}
@@ -1881,7 +1881,7 @@
 			return 1;
 		}
 		else { /* unknown "disable" parameter */
-			appctx->ctx.cli.msg = "'disable' only supports 'frontend' and 'server'.\n";
+			appctx->ctx.cli.msg = "'disable' only supports 'agent', 'frontend' and 'server'.\n";
 			appctx->st0 = STAT_CLI_PRINT;
 			return 1;
 		}