Remove fybrik.io/crdoc dependency as it is causing issues for folks attempting
to vendor tailscale using GOPROXY=direct.
This means that the CRD API docs in ./k8s-operator/api.md will no longer
be generated- I am going to look at replacing it with another tool
in a follow-up.
Updates tailscale/tailscale#12859
Signed-off-by: Irbe Krumina <irbe@tailscale.com>