ipfs cluster follow

[coryschwartz]

Adds a feature for joining collab clusters.

instructions on ipfs-cluster-follow can be seen here: https://ipfscluster.io/documentation/reference/follow/

Some of the collab clusters can be seen here https://collab.ipfscluster.io/

The way it's used in this PR --
For every collab cluster you want to follow, add the name and the template to the Follows slice.

An instance of ipfs-cluster-follow will be executed on your cluster for each follow you specify.

e.g. This will create an additional container responsible for following filecoin proofs.

follows:
  - name: filecoin
    template: filecoin.collab.ipfscluster.io

Templates must be created in advance by the collab cluster operator. This one can be seen at https://ipfs.io/ipns/filecoin.collab.ipfscluster.io

[RobotSail]

Looks good, just one minor change and this should be all set.