MINOR: Fix a typo in a warning message in the spoe subsystem

Fix a typo in a user-facing message of the spoe subsystem.
diff --git a/src/flt_spoe.c b/src/flt_spoe.c
index 5b66e8f..02bc3d2 100644
--- a/src/flt_spoe.c
+++ b/src/flt_spoe.c
@@ -3974,7 +3974,7 @@
 		else if (!strcmp(args[1], spoe_event_str[SPOE_EV_ON_HTTP_RSP]))
 			curmsg->event = SPOE_EV_ON_HTTP_RSP;
 		else {
-			ha_alert("parsing [%s:%d] : unkown event '%s'.\n",
+			ha_alert("parsing [%s:%d] : unknown event '%s'.\n",
 				 file, linenum, args[1]);
 			err_code |= ERR_ALERT | ERR_FATAL;
 			goto out;