Webcast handbook documentation updates

Why is this change being made?

Updating webcast handbook documentation <!--

Describe in detail answer to question on why this change is being proposed, in accordance with our value of Transparency

--> Updating to add clarity on form to use for upcoming webcast and access to the webcast yml

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