New-Restful-Plan.md

 | Endpoint | Type | Example(s) |
 |----------|:----:|----------|
 | /login | POST | [Successful](New-Restful-Plan#login-successful) <br></br> [Failed](New-Restful-Plan#login-failed) |
-| /logout | POST | [Successful](New-Restful-Plan#logout-successful) |
+| /logout | POST | [Successful](New-Restful-Plan#logout-successful) <br></br> [Failed](New-Restful-Plan#logout-failed)|
 | /quests | GET | [Successful](New-Restful-Plan#quest-list) |
 | /quests/create | POST |  |
 | /quests/{questID} | GET |  |
@@ -80,6 +80,24 @@ POST /logout
 Player 41 logged out.
 ```
 
+# Logout - Failed
+## Request
+```http
+POST /logout
+```
+
+## Payload
+```json
+{
+  "playerID": 41
+}
+```
+
+## Response
+```plaintext
+Player 41 failed to log out.
+```
+
 # Quest List
 ## Request
 ```http