Update part6d.md: Clarify the usage of server.js in exercise 6.20

Clarify the usage of server.js in exercise 6.20.
Added due to discrepancy between the exercise code and screenshots

Author: SebastianEShelby

src/content/6/en/part6d.md

@@ -365,7 +365,7 @@ Most React applications need not only a way to temporarily store the served data
 
 ### Exercises 6.20.-6.22.
 
-Now let's make a new version of the anecdote application that uses the React Query library. Take [this project](https://github.com/fullstack-hy2020/query-anecdotes) as your starting point. The project has a ready-installed JSON Server, the operation of which has been slightly modified. Start the server with <i>npm run server</i>.
+Now let's make a new version of the anecdote application that uses the React Query library. Take [this project](https://github.com/fullstack-hy2020/query-anecdotes) as your starting point. The project has a ready-installed JSON Server, the operation of which has been slightly modified (Review the _server.js_ file for more details. Make sure you're connecting to the correct _PORT_). Start the server with <i>npm run server</i>.
 
 #### Exercise 6.20