new PR template

Author: nicolaskruchten

.github/pull_request_template.md

@@ -1,5 +1,6 @@
 Doc upgrade checklist:
 
+- [ ] file has been moved from `unconverted/x/y.md` to `x/y.md`
 - [ ] old boilerplate at top and bottom of file has been removed
 - [ ] Every example is independently runnable and is optimized for short line count
 - [ ] no more `plot()` or `iplot()`
@@ -9,5 +10,4 @@ Doc upgrade checklist:
 - [ ] liberal use of `add_trace` and `update_layout`
 - [ ] `fig.show()` at the end of each example
 - [ ] `px` example at the top if appropriate
-- [ ] `v4upgrade: true` metadata added
 - [ ] minimize usage of hex codes for colors in favour of those in https://github.com/plotly/plotly.py-docs/issues/14