Fix Doxygen links in WifiInterface.md

Point links to class reference instead of .h file.

Author: Amanda Butler

docs/api/networkinterfaces/WifiInterface.md

@@ -1,10 +1,12 @@
 ## Wi-Fi
 
+<span class="images">![](http://os.mbed.com/docs/development/mbed-os-api-doxy/class_wi_fi_interface.png)<span>WiFiInterface class hierarchy</span></span>
+
 The WifiInterface provides a simple C++ API for connecting to the internet over a Wi-Fi device.
 
 ### Wi-Fi class reference
 
-[![View code](https://www.mbed.com/embed/?type=library)](https://os.mbed.com/docs/development/mbed-os-api-doxy/_wi_fi_interface_8h_source.html)
+[![View code](https://www.mbed.com/embed/?type=library)](http://os.mbed.com/docs/development/mbed-os-api-doxy/class_wi_fi_interface.html)
 
 ### Usage