Update GitLab 101 link to point to GitLab 101 certification

What does this MR do and why?

The GitLab 101 link on this tutorials page was pointing to an old link. The error "You do not have permission to access this Pathway. Please reach out to the user who has shared this Pathway with you to provide access." was received when following the link and login into EdCast.

I've found a GitLab 101 Certification course on GitLab's EdCast which matches the GitLab 201 link.

Screenshots or screen recordings

GitLab 101 broken link location:

Before:

After:

How to set up and validate locally

1. Navigate to https://docs.gitlab.com/ee/tutorials/
2. Click on GitLab 101 link
3. Create an account or sign into GitLab EdCast

Expected results

• A tutorial for GitLab 101

Actual results

• An error received "You do not have permission to access this Pathway. Please reach out to the user who has shared this Pathway with you to provide access."

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.