Added access request url to 'index' and updated info in renewal.md

For commercial accounts, we do not currently offer our customers Slack channels unless they meet specific criteria and it would be highly beneficial to both the customer and GitLab teams.

Prior to creating the channel and provisioning access for an existing account, the CSM for the account must approve its creation and use.

Prior to creating the channel and provisioning access for an existing account, the CSM for the account must approve its creation and use. You can provision a new slack channel via an [access request](https://gitlab.com/gitlab-com/team-member-epics/access-requests/-/issues?sort=created_date&state=opened&first_page_size=100)

If the customer is evaluating GitLab or doing a POV for an upgrade, it may be worthwhile to create an ephemeral Slack channel, but the channel should be closed within 90 days and/or at project completion. The SA must approve the creation and use, with the expectation that it may be used only during the pre-sales process.

A "Renewal Review" meeting should have the following attendees:

- Account Executive

- Solutions Architect

- Renewals Manager

- Customer Success Manager

For strategic accounts (with a ACV over $100k) the following attendees should be added as well:

- Regional Sales Director

- CSM Regional Manager

The agenda of a "Renewal Review" meeting should include at least the following:

 1. Review of the customer health score and any changes over the past few months - changes can be seen in the Timeline in Gainsight.

 1. Review of high priority feature requests.

 1. Review of the customer's utilization of the product.

 1. Review of any changes in customer's budget or staffing.

 1. Review recent customer news (layofss, acquisitions, etc)

From this meeting a set of action items should be created to improve customer utilization and satisfaction with the product.  These items can include: