Add annotations for event bus settings

[robrap]

AC:

• Add annotation documentation for the rest of the settings in config.py.

Only one of the settings in config.py is annotated:

event-bus-kafka/edx_event_bus_kafka/internal/config.py

Lines 88 to 95 in bb4262f

	# .. setting_name: EVENT_BUS_TOPIC_PREFIX
	# .. setting_default: None
	# .. setting_description: If provided, add this as a prefix to any topic names (delimited by a hyphen)
	# when either producing or consuming events. This can be used to support separation of environments,
	# e.g. if multiple staging or test environments are sharing a cluster. For example, if the base topic
	# name is "user-logins", then if EVENT_BUS_TOPIC_PREFIX=stage, the producer and consumer would instead
	# work with the topic "stage-user-logins".
	topic_prefix = getattr(settings, 'EVENT_BUS_TOPIC_PREFIX', None)

This ticket is for adding annotations for the rest of the settings in this file.
https://github.com/openedx/event-bus-kafka/blob/main/edx_event_bus_kafka/internal/config.py

We might want to link to the new annotations from:

• https://github.com/openedx/event-bus-kafka#documentation
• https://openedx.atlassian.net/wiki/spaces/AC/pages/3508699151/How+to+start+using+the+Event+Bus#First-time-setup

Note: We could consider updating docs in this library to extract/publish these annotations, as is done in edx-platform. This could be part of this ticket or its own ticket.

[robrap]

Should we do this now, or add to Future milestone?

[timmc-edx]

Created #139 for followup.