Better disclaimer

Doc/Sda1/prerequisites.xml

@@ -41,7 +41,8 @@
           xlink:href="https://freedocs.mi.hdm-stuttgart.de/index.jsp?topic=/de.hdm_stuttgart.mi.freedocs/printversion.pdf">https://freedocs.mi.hdm-stuttgart.de/index.jsp?topic=/de.hdm_stuttgart.mi.freedocs/printversion.pdf</uri></para>
 
           <caution>
-            <para>Some figures and videos are left blank.</para>
+            <para>Some content like videos in the printable version of these
+            lecture notes may be left blank.</para>
           </caution>
         </glossdef>
       </glossentry>