Minor grammar change: Improve ReviewRemindersDatabase docstrings

GSoC 2025: Review Reminders

- Fixed some wording in a single docstring in ReviewRemindersDatabase on David's suggestion

Author: ericli3690

AnkiDroid/src/main/java/com/ichi2/anki/reviewreminders/ReviewRemindersDatabase.kt

@@ -71,7 +71,7 @@ class ReviewRemindersDatabase {
 
     /**
      * Get the [ReviewReminder]s for a specific key.
-     * @throws SerializationException If the value associated to this key is not a string encoding valid JSON.
+     * @throws SerializationException If the value associated with this key is not valid JSON string.
      * @throws IllegalArgumentException If the decoded reminders map is not a HashMap<[ReviewReminderId], [ReviewReminder]>.
      */
     private fun getRemindersForKey(key: String): HashMap<ReviewReminderId, ReviewReminder> {