update 1.x README to point to 2.x repo (#2416)
update 1.x README to point to 2.x repo (#2416)

* update 1.x README to point to 2.x repo

Signed-off-by: William Morgan <c824fe0afe16857dd6f587aa7c4044d2642d60fb@buoyant.io>

Co-authored-by: Peter Fröhlich <2d50111f4bd7ae0d7a69ff28b23a999fab45c113@tarwin.de>

linkerd/linkerd,linkerd/linkerd,linkerd/linkerd