Add redirect for documentation

Not clear what links to this page but let's just redirect it anyway.

Closes 8640

Author: robmen

src/Web/appsettings.json

@@ -66,6 +66,7 @@
     { "docs/reference/api/(.*)": "/docs/api/$1" },
     { "docs/reference/(.*)": "/docs/tools/$1" },
     { "docs/fourthree_bundles": "docs/fourthree/faqs" },
+    { "documentation": "/docs/intro/" },
     { "*img/logo.gif": "content/logo.gif" },
     { "*projectaggregator2.msi": "http://static.wixtoolset.org/releases/ProjectAggregator2/ProjectAggregator2.msi" },
     { "*votive.html": "/docs/v3/votive/" },