Add legal notice to the footer

themes/exectos/layouts/partials/footer.html

@@ -4,6 +4,7 @@
 					Copyright© 2017 - 2024, CodingWorkshop
 				</div>
 				<div class="footer-right">
+				    Content is available under <a href="https://www.gnu.org/licenses/fdl-1.3.html">GNU Free Documentation License 1.3 or later</a>.
 				</div>
 			</div>
 		</div>