Adding talent brand resources

Why is this change being made?

Adding a section to the talent brand page that can be "home" to resources that help people talk about life at GitLab. This includes links to the:

• Hiring fact sheet
• Article repo
• Talent ambassadors page

This MR also adds a cross-link to this new "talent brand resources" section in the:

• "Conducting a GitLab interview" section of the /hiring/interview page
• "How to source candidates" section of the /hiring/sourcing page.

Cc @davegilbert @Apshegodskaya @Ahoffbauer

Does this MR meet the acceptance criteria?

Conformity

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