Document MDS Indexing Setup for multiple index nodes

Consider the following exchange from a customer:

I built a Centos7, CB4.0 4 node cluster, with all three services (data, indexing, query) on each node
10.112.100.101
10.112.100.102
10.112.100.103
10.112.100.104
I created two named primary indexes by:

CREATE PRIMARY INDEX p101 ON `travel-sample` USING GSI WITH

{"nodes": "10.112.100.101:8091"}

CREATE PRIMARY INDEX p102 ON `travel-sample` USING GSI WITH

{"nodes": "10.112.100.102:8091"}

I am able to verify that I'm able to see those from the UI, and from the CLI:

SELECT name,is_primary FROM system:indexes;
{
"requestID": "0dadfedc-35e9-4826-9077-c893477a0ad8",
"signature":

{ "is_primary": "json", "name": "json" }

,
"results": [

{ "is_primary": true, "name": "p101" }

,

{ "is_primary": true, "name": "p102" }