Update board descriptions on Progressive Delivery Group page

Why is this change being made?

The descriptions of our boards including links are/were out of date as we have updated our processes. This MR proposes those updates.

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