Grammar fix to remove repeated word in subredditManager.js (#5545)

Changes "may take a a few seconds" to "may take a few seconds", removing the repeated "a".

lib/modules/subredditManager.js

@@ -929,7 +929,7 @@ const srList = once(() => {
 		return element;
 	}
 
-	element.append(string.html`<div>Loading subreddits ... (may take a a few seconds)</div>`);
+	element.append(string.html`<div>Loading subreddits ... (may take a few seconds)</div>`);
 
 	getMySubredditsTable(user).then(table => {
 		empty(element);