[DOCS] Fixes missing colon (#52797)

x-pack/docs/en/watcher/trigger/schedule/daily.asciidoc

@@ -63,7 +63,7 @@ For example, the following `daily` schedule triggers once every day at 5:00 PM:
   "trigger" : {
     "schedule" : {
       "daily" : {
-        "at" {
+        "at" : {
           "hour" : 17,
           "minute" : 0
         }
@@ -93,4 +93,4 @@ or minutes as an array. For example, following `daily` schedule triggers at
   }
 }
 --------------------------------------------------
-// NOTCONSOLE
+// NOTCONSOLE