Rate Limit Documentation needs improvement

toIssue Summary

This is reproducible on Data Center: yes

Steps to Reproduce

1. In section "Rate limiting technique we've chosen" of doc Improving instance stability with rate limiting, it is mentioned that Users get new tokens at a constant rate so they can keep making new requests. This is their Requests allowed, and can be, for example, 10 every 1 minute.. But what that constant rate is not defined anywhere. We should mention in doc that This constant interval is Time interval(in second) divided by Request allowed.
2. We should also mention in doc that when we set "Per time" in UI for Rate Limit configuration, irrespective of options of Seconds, Minutes and Hours, Jira Always translates time interval in seconds i.e. token is sent to user in constant interval which allows him to send successful request i.e. Time interval(in second) divided by Request allowed.
3. We should also describe How retry-after response header is calculated. Because user is allowed to send a request successfully when retry-after header is set to 0 after several failures with http status code 429.

Expected Results

Users are sometimes mislead with the documentation that a user will be able to send only configured number of request per time(it can be configured in second, minute or hour).

Actual Results

User are able to send more number of request than configured in Rate Limit per time.

Workaround

KB article
Jira Rate Limiting is not working as configured describes Rate Limit functionality with example.