Update mg_dns_copy_questions.md

docs/c-api/dns.h/mg_dns_copy_questions.md

@@ -6,10 +6,10 @@ signature: |
   int mg_dns_copy_questions(struct mbuf *io, struct mg_dns_message *msg);
 ---
 
-Append already encoded questions from an existing message.
+Appends already encoded questions from an existing message.
 
 This is useful when generating a DNS reply message which includes
 all question records.
 
-Return number of appened bytes. 
+Returns the number of appened bytes.