hledger/.github/pull_request_template.md

Thanks for your pull request! We appreciate it. 
If you're a new developer, FOSS contributor, or hledger contributor, welcome.

Much of our best design work and knowledge sharing happens during code review,
so be prepared for more work ahead, especially if your PR is large.
To minimise waste, and learn how to get hledger PRs accepted swiftly, 
please check the latest guidelines in the developer docs:

https://github.com/simonmichael/hledger/wiki/Pull-requests