Projects: deprecate unmaintained list

The list of projects is pretty stale, with few updates,
and even the links to other lists is also stale too.
Over the years, awesome-go appears to be the best community mainted
resource for Go projects in general, so link to that instead.

Change-Id: If0969748e40a047b895319329723adf7167d4bc6
Reviewed-on: https://go-review.googlesource.com/c/wiki/+/665256
Reviewed-by: Sean Liao <sean@liao.dev>