Update changelog to include JSON schema addition

CHANGELOG.md

@@ -4,6 +4,12 @@ If there is no "Upgrading" header for that version, no post-upgrade actions need
 
 
 ## Upcoming
+### New Features
+- A [JSON Schema](https://json-schema.org/) definition was added to help users validate their configuration files through updates
+([#320](https://github.com/jdholtz/auto-southwest-check-in/pull/320) by [@kaveet](https://github.com/kaveet))
+    - If you want to use this schema, you'll need to add the following line to your `config.json` file:
+    `"$schema": "config.schema.json"`
+
 ### Improvements
 - Logins that fail due to 'Too Many Requests' or 'Internal Server Error' errors will now be retried once
 ([#311](https://github.com/jdholtz/auto-southwest-check-in/pull/311) by [@dmytrokoren](https://github.com/dmytorkoren))

CONFIGURATION.md

@@ -11,7 +11,7 @@ reservation-specific configurations).
 ## Table of Contents
 - [Check Fares](#check-fares)
 - [Notifications](#notifications)
-    * [Notification URLS](#notification-urls)
+    * [Notification URLs](#notification-urls)
     * [Notification Level](#notification-level)
     * [Notification 24 Hour Time](#notification-24-hour-time)
     * [Test The Notifications](#test-the-notifications)
@@ -187,7 +187,7 @@ Setting specific configuration values for an account or reservation allows you t
 monitored by the script. Here is a list of configuration values that can be applied to an individual account or reservation:
 - [Check Fares](#check-fares)
 - [Healthchecks URL](#healthchecks-url)
-- [Notification URLS](#notification-urls)
+- [Notification URLs](#notification-urls)
 - [Notification Level](#notification-level)
 - [Retrieval Interval](#retrieval-interval)