website: link ecosystem from edge (#6170)

Edge works fine, so we'll do this:

1. link to /docs/edge/ecosystem
2. suppress the "you're viewing edge" banner from the
   ecosystem page

We can revisit this when the next release is out, but it
makes the ecosystem page _less broken_ for the time until
then.

Signed-off-by: Stephan Renatus <stephan@styra.com>