9.3
documentation: Revise uses of "e.g.," followed by a colon.
docs: Add comma to all uses of "e.g." in contributor docs.
docs: Rename `user.md` to `helpcenter.md`.
integration-docs: Clarify use of event-filtering-additional-feature.
docs: Correct path to zulip.yaml.
documentation: Modify cases of "[a-zA-Z] e\.g\.," for readability.