Folks, I have produced some useful templates for the past five years that have helped my teams organize documentation ranging from incident reports (post-mortem), how-to guides, Architectural Decision Records (ADRs), and personnel onboarding (30-60-90) plans.
You can see some examples in the following screenshots. The examples are in Portuguese, but I would surely translate them into English before sharing. Most of them use the page properties macro, which enabled us to create listings that are easy to browse. It is really useful to check the history of incidents, to check who was the onboarding buddy partner of a recently hired employee, and so on.
I saw templates shared by other companies like Hubspot, but I could not find any information on how to submit templates for Atlassian consideration.
Incident Report
An incident record describes the impact of the incident and further actions to prevent it from happening in the future.
Listing of incident reports (redacted). The page properties macro is useful. 
Architectural Decision Record
An architecture decision record (ADR) is a document that captures an important architectural decision made along with its context and consequences.
Onboarding 30-60-90 plan
We always define a buddy who is responsible for helping the new employee in their first three months (hence 30-60-90 in the name). The plan includes people the new hire should meet, documents that must be read, and other useful instructions.
OKRs and roadmap
A well-formatted page to summarize the OKRs and roadmap of a given period of time.
