Add Wiki and Snippets to project feature overview

doc/user/project/index.md

@@ -72,6 +72,8 @@ website with GitLab Pages
 
 **Other features:**
 
+- [Wiki](wiki/index.md): Document your GitLab project in an integrated Wiki
+- [Snippets](../snippets.md): Store, share and collaborate on code snippets
 - [Cycle Analytics](cycle_analytics.md): Review your development lifecycle
 - [Syntax highlighting](highlighting.md): An alternative to customize
 your code blocks, overriding GitLab's default choice of language