[FW][IMP] events: update track and manage talks

[fw-bot]

PROJECT TASK: https://www.odoo.com/web#id=3915122&cids=3&menu_id=4720&action=333&active_id=3835&model=project.task&view_type=form

This PR discuss what the Talks, Talk Proposals, and Agenda event website pages entail -- and how to utilize and navigate them. This is meant as a supplemental PR to the 'Create event tracks' doc...which is focused more on the backend elements and how to create tracks for an event.

This PR should be published/merged after the 'event_tracks' PR That's why there is likely going to be continued Build Errors -- because that 'event_tracks' doc is referenced in the seealso at the end.

I worked off the original RST file name so that I didn't ruin any potential reference links that could be lingering elsewhere...

Forward-Port-Of: odoo/documentation#9223

[robodoo]

[fw-bot]

@ksc-odoo cherrypicking of pull request odoo/documentation#9223 failed.

stdout:

Auto-merging content/applications/marketing/events/track_manage_talks.rst
CONFLICT (content): Merge conflict in content/applications/marketing/events/track_manage_talks.rst

stderr:

05:35:00.361179 git.c:463               trace: built-in: git cherry-pick 7e23c643bbbd06bc337b3232a82205975cec538e --strategy ort
error: could not apply 7e23c643b... [IMP] events: update track and manage talks
hint: After resolving the conflicts, mark them with
hint: "git add/rm <pathspec>", then run
hint: "git cherry-pick --continue".
hint: You can instead skip this commit with "git cherry-pick --skip".
hint: To abort and get back to the state before "git cherry-pick",
hint: run "git cherry-pick --abort".
----------
status:

Either perform the forward-port manually (and push to this branch, proceeding as usual) or close this PR (maybe?).

In the former case, you may want to edit this PR message as well.

:warning: after resolving this conflict, you will need to merge it via @robodoo.

More info at https://github.com/odoo/odoo/wiki/Mergebot#forward-port

[fw-bot]

@ksc-odoo this forward port of odoo/documentation#9223 is awaiting action (not merged or closed).