Everything is described in this link
I think this is very useful to be implemented because sqlmap devs can set some sort of rules/questions which users must answer. It will be some sort of guide to write a correct and helpful issue. Devs will save time, knowing additional info about issue, and no need to ask a user with additional questions about (for example) OS, version....
Examples from other project on GitHub:
Example of ISSUE_TEMPLATE file
How it shows to users when creating new issue
How it looks like when issue is created:
Implementation for an Issue #2221
With the latest commit New Issue (templated) page should look like: