Update part3a.md

Author: taaalha

src/content/3/en/part3a.md

@@ -883,6 +883,10 @@ Implement a page at the address <http://localhost:3001/info> that looks roughly
 ![Screenshot for 3.2](../../images/3/23x.png)
 
 The page has to show the time that the request was received and how many entries are in the phonebook at the time of processing the request.
+  
+Proposed Addition: There can only be one response.send() statement in an Express app route. Once you send a response to the client using response.send(), the request-response cycle is complete and no further response can be sent. 
+  
+To include a line space in the output, use <br/> tag, or wrap the statements in <p> tags.
 
 #### 3.3: Phonebook backend step3