Add Firefox add-on link to TAM support page

Why is this change being made?

Firefox users should also profit from the Zendesk-Ticket redirect. This MR adds the Firefox Redirector add-on link to the TAM support 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