add WiFi link

Author: vladak

docs/exams.html

@@ -30,7 +30,7 @@ <h3>Prerequisites</h3>
 <p>If you did not attend the labs, be sure to check that your Unix lab account
 works (try to sign in using SSH).  You can work on your laptop and send us your
 solution via email when you are done.  If using your laptop, make sure you can
-connect to wifi in the labs though.
+connect to <a href="https://www.mff.cuni.cz/cs/math/vnitrni-zalezitosti/pocitace-a-technika/wi-fi">wifi</a> in the labs though.
 
 <h3>Dates</h3>