Create handbook page for content in campaigns

Why is this change being made?

Create handbook page for how we leverage content in campaigns (specifically calling out changes to ungated content journeys and preserving instructions for gated content landing pages). Taking a FRESH perspective on this and looking for opportunities to make steps more efficient (or cut them out) and discover what we can pass to Verticurl in Marketo.

❗ as this is merged, we will deprecate the old gated content page and point here.

To note (somewhat mental note for jackie):

• Considering whether we truly need Marketo programs with listening (to clearly filter out sending emails to people who have recently engaged with something) or if this is just extraneous and we don't need it.
  • the alternative to consider/test is if we can use whatever the "listener" trigger would be and use that as a filter for the sends. makes this more efficient and pulls out steps of program creation
  • something worth noting is that SDRs/sales wouldn't be able to scan SFDC campaign membership to discover what someone engaged with at a glance - would need to look at Marketo section.

cc @zbadgley NO ACTION needed right now - ignore this almost entirely, but just wanted you to know that I'm working on moving the gated content page over to campaigns (and reframing as "content in campaigns").

cc @rragozzine NO ACTION needed right now - likewise, you'll see a lot of changes to how we broke out analyst relations (by not breaking out, for more simplicity) - I have a meeting so just getting V1 in and I'm going to keep playing with this in the afternoon to crank it out, then examine from your POV to see where we can make this more clear, more efficient, efficient, and think through if we need to keep AR separated out. So again, no need to comment until I give this a second view because I might completely pull it apart and put it back together!

Author Checklist

• Provided a concise title for the MR
• Added a description to this MR explaining the reasons for the proposed change, per say-why-not-just-what
• Assign this change to the correct DRI
  • If the DRI for the page/s being updated isn’t immediately clear, then assign it to one of the people listed in the "Maintained by" section in on the page being edited.
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