Update mg_coap_free_options.md

docs/c-api/coap.h/mg_coap_free_options.md

@@ -6,6 +6,6 @@ signature: |
   void mg_coap_free_options(struct mg_coap_message *cm);
 ---
 
-Free the memory allocated for options,
-if cm paramater doesn't contain any option does nothing. 
+Frees the memory allocated for options.
+If the cm paramater doesn't contain any option it does nothing.