Webpack.js.org: Document webpack change: Improve pull request template and add automatic issue to docs

[webpack-bot]

A pull request by @sokra was merged and maintainers requested a documentation change.

See pull request: https://github.com/webpack/webpack/pull/7307

---

What kind of change does this PR introduce?
bot and template

Did you add tests for your changes?
N/A

Does this PR introduce a breaking change?
no

What need to be documented once your changes are merged?
nothing (but I still let the bot send a issue to try to workflow)

[sokra]

ok seem to work 😄

[EugeneHlushko]

:D