add /go/experimental/ redirect

We already have a redirect for this that's defined in the docker/cli repository,
but unifying these redirects to live in the docs repository.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

Author: thaJeztah

go/experimental.md

@@ -0,0 +1,4 @@
+---
+description: Redirect refer users on how to enable experimental CLI features (now enabled by default)
+redirect_to: /engine/reference/commandline/cli/#experimental-features
+---