remove typos

Author: Dhruvi16

themes/vocabulary_theme/templates/layout.html

@@ -230,7 +230,7 @@
                     <a href="{{ '/blog'|url }}" class="menu-item">Blog</a>
                   </li>
                   <li>
-                    <a href="{{ '/contributing-code'|url }}" class="menu-item">Contributing Guidelines</a>
+                    <a href="{{ '/contributing-code'|url }}" class="menu-item">Contribution Guidelines</a>
                   </li>
                   <li>
                     <a href="{{ '/community/community-team'|url }}" class="menu-item">Community Teams</a>