Update GitHub wording in navbar (cortexproject#5518)

Signed-off-by: Chanaka Lakmal <[email protected]>

Author: ldclakmal

website/layouts/partials/navbar.html

@@ -34,7 +34,7 @@
 			</li>
 			<li class="nav-item mr-4 mb-2 mb-lg-0">
 				<a href="https://github.com/cortexproject" class="nav-link active">
-					<span class="active"><i class="fab fa-fw fa-github"></i> Github</span>
+					<span class="active"><i class="fab fa-fw fa-github"></i> GitHub</span>
 				</a>
 			</li>
 		</ul>