add title to license image

Author: gregor-j

_layouts/default.html

@@ -24,7 +24,7 @@ <h2 class="project-tagline">{{ site.description | default: site.github.project_t
     {{ content }}
 
     <footer class="site-footer">
-        <span class="site-footer-credits">This page was generated by <a href="https://pages.github.com">GitHub Pages</a> and is maintained by <a href="https://github.com/gregor-j">Gregor J.</a> <a rel="license" href="http://creativecommons.org/licenses/by-sa/4.0/"><img alt="This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License" style="border-width:0" src="https://i.creativecommons.org/l/by-sa/4.0/80x15.png" /></a> Diagrams have been created using <a href="https://www.planttext.com/">PlantText UML Editor</a>.</span>
+        <span class="site-footer-credits">This page was generated by <a href="https://pages.github.com">GitHub Pages</a> and is maintained by <a href="https://github.com/gregor-j">Gregor J.</a> <a rel="license" href="http://creativecommons.org/licenses/by-sa/4.0/"><img alt="Creative Commons License" title="This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License" style="border-width:0" src="https://i.creativecommons.org/l/by-sa/4.0/80x15.png" /></a> Diagrams have been created using <a href="https://www.planttext.com/">PlantText UML Editor</a>.</span>
     </footer>
 </main>
 </body>