chore(PULL_REQUEST_TEMPLATE): better checklist + 4 agreements (#4547)

PULL_REQUEST_TEMPLATE.md

@@ -2,14 +2,16 @@
 
 > Check items when done or if not relevant
 
-- [ ] PR reference the relevant issue (e.g. `Fixes #007`)
+- [ ] PR reference the relevant issue (e.g. `Fixes #007` or `See xoa-support#42`)
 - [ ] if UI changes, a screenshot has been added to the PR
-- [ ] if `xo-server` API changes, the corresponding test has been added to/updated on [`xo-server-test`](https://github.com/vatesfr/xen-orchestra/tree/master/packages/xo-server-test)
-- [ ] `CHANGELOG.unreleased.md`:
-   - enhancement/bug fix entry added
-   - list of packages to release updated (`${name} v${new version}`)
 - [ ] documentation updated
-- [ ] **I have tested added/updated features** (and impacted code)
+- `CHANGELOG.unreleased.md`:
+  - [ ] enhancement/bug fix entry added
+  - [ ] list of packages to release updated (`${name} v${new version}`)
+- **I have tested added/updated features** (and impacted code)
+  - [ ] unit tests (e.g. [`cron/parse.spec.js`](https://github.com/vatesfr/xen-orchestra/blob/b24400b21de1ebafa1099c56bac1de5c988d9202/%40xen-orchestra/cron/src/parse.spec.js))
+  - [ ] if `xo-server` API changes, the corresponding test has been added to/updated on [`xo-server-test`](https://github.com/vatesfr/xen-orchestra/tree/master/packages/xo-server-test)
+  - [ ] at least manual testing
 
 ### Process
 
@@ -17,3 +19,10 @@
 1. mark it as `WiP:` (Work in Progress) if not ready to be merged
 1. when you want a review, add a reviewer (and only one)
 1. if necessary, update your PR, and re- add a reviewer
+
+From [_the Four Agreements_](https://en.wikipedia.org/wiki/Don_Miguel_Ruiz#The_Four_Agreements):
+
+1. Be impeccable with your word.
+1. Don't take anything personally.
+1. Don't make assumptions.
+1. Always do your best.