Add links to walkthrough of Nexus OSS

Why is this change being made?

As part of our Q1 OKRs I created a walkthrough of Nexus Repository Manager. This MR adds that series of videos to our team page.

Does this MR meet the acceptance criteria?

Assign to DRI

• Did you assign this change to the correct DRI of the page or information you are changing?

Conformity

• Added description to this MR explaining the reasons for the proposed change, per say-why-not-just-what