Vastly simplify PR template (canonical#964)

.github/pull_request_template.md

@@ -1,35 +1 @@
-## Please provide the following details to expedite review (and delete this heading)
-
-*Replace with a description about why this change is needed, along with a description of what changed.*
-
-## Checklist
-
- - [ ] Have any types changed? If so, have the type annotations been updated?
- - [ ] If this code exposes model data, does it do so thoughtfully, in a way that aids understanding?
-
-       We want to avoid simple passthrough of model data, without contextualization, where possible.
-
- - [ ] Do error messages, if any, present charm authors or operators with enough information to solve the problem?
-
-## QA steps
-
-*Please replace with how we can verify that the change works.*
-
-```sh
-QA steps here
-```
-
-## Documentation changes
-
-*Please replace with any notes about how it affects current user workflow, CLI, or API.*
-
-## Bug reference
-
-*Please add a link to any bugs that this change is related to, e.g., https://bugs.launchpad.net/juju/+bug/9876543*
-
-## Changelog
-
-*Please include a bulleted list of items here, suitable for inclusion in a release changelog.*
-
-- *Adds feature foo, which allows charm authors to ...*
-- *Fixes bug bar, which means that operators no longer need workaround qux ...*
+Please describe the *why* and the *how* of your change here.