Add List Members collection to public docs (#4692)

* Add List Members Collection to docs - Update index.md

Added the list members collection to the docs, as success eng is able to manually sync this collection for customer.

Relevant JIRA: https://segment.atlassian.net/browse/SRC-364

* Update index.md

edit list members collection

Author: charholt

src/connections/sources/catalog/cloud-apps/mailchimp/index.md

@@ -44,5 +44,6 @@ Collections are the groupings of resources we pull from your source. In your war
 |  ------ | ------ | ------ |
 |  `conversations` | object | Conversation tracking is a [paid feature](http://kb.mailchimp.com/accounts/billing/how-mailchimp-pricing-plans-work) that lets you view subscribers' replies to your campaigns from inside your MailChimp account. Fetched using Mailchimp's [`/conversations`endpoint](https://mailchimp.com/developer/reference/conversations/). |
 |  `lists` | object | The state of your various lists in Mailchimp. Fetched using Mailchimp's [`/lists` endpoint](https://mailchimp.com/developer/reference/lists/). |
+|  `list members` | object | Get the list of members in a MailChimp list. Fetched using Mailchimp's [`/lists` endpoint] If you are interested in this collection, [contact Segment Support](https://segment.com/help/contact/) |
 |  `campaigns` | object | Your Mailchimp campaigns. Fetched using Mailchimp's [`/campaigns` endpoint](https://mailchimp.com/developer/reference/campaigns/). |
 |  `subscriber activity` | object | **Currently unavailable** Mailchimp's subscriber activity endpoint cannot support our Sources product. If you are interested in this collection, contact your MailChimp Client Success Manager and request that they update their export API functionality.* |