added GitHub links to manual

manual.html

@@ -91,9 +91,9 @@ <h2>Shortcuts</h2>
 <section>
   <h2>Bugs and Suggestions</h2>
 
-  <p>Please report bugs, wrong reflection data, etc. or suggestions to landvogt [at] uni-bonn.de</p>
+  <p>Please report bugs, wrong reflection data, etc. or suggestions to landvogt [at] uni-bonn.de or open an issue at the <a href="https://github.com/lvogt/jsHKL/">GitHub repository</a></p>
 
-  <p>This program is distributed under the terms of the <a href="LICENSE.txt">GNU General Public License v3</a>. A ZIP archive with all relevant files is available <a href="jsHKL-2017-06-26.zip" download >here</a>.</p>
+  <p>This program is distributed under the terms of the <a href="LICENSE.txt">GNU General Public License v3</a>. The newest release is available <a href="https://github.com/lvogt/jsHKL/releases/latest/">here</a>.</p>
 
   <p>Copyright &copy; 2016, 2017 Christian Landvogt</p>  
 </section>