Update user query feature (#3338)

* Change user query wording

There was some misunderstanding in the use of the user query feature,
probably because of the wording. I've change it to make it more obvious.

* Fix feedback when a query is bookmarked

Before, the displayed query name was not the one intended. Now, the name is the one of the current bookmark

* Document user queries

I've added a few words on how to use the user queries because it seems there was some misunderstanding. See #3219

app/Models/UserQuery.php

@@ -42,7 +42,7 @@ class FreshRSS_UserQuery {
 		if (!isset($query['search'])) {
 			$query['search'] = '';
 		}
-		// linked to deeply with the search object, need to use dependency injection
+		// linked too deeply with the search object, need to use dependency injection
 		$this->search = new FreshRSS_BooleanSearch($query['search']);
 		if (isset($query['state'])) {
 			$this->state = $query['state'];