docs: Add text to sidebar

Author: TiagoCavalcante

docs/_includes/Sidebar.html

@@ -16,6 +16,7 @@
 					<li><a href="/mathics-threejs-backend/primitives/point">point</a></li>
 					<li><a href="/mathics-threejs-backend/primitives/polygon">polygon</a></li>
 					<li><a href="/mathics-threejs-backend/primitives/sphere">sphere</a></li>
+					<li><a href="/mathics-threejs-backend/primitives/text">text</a></li>
 					<li><a href="/mathics-threejs-backend/primitives/tube">tube</a></li>
 					<li><a href="/mathics-threejs-backend/primitives/uniformPolyhedron">uniform&shy;Polyhedron</a></li>
 				</ul>