github: add a reproduction environment to the issue template (#354)

- this should help make reproductions easier as it gives a quick
  starting point requiring no boilerplate and is easily accessible from
  a browser too

- decided to go with StackBlitz over CodeSandbox and repl.it as it's
  WebContainer tech allows for running Node projects entirely _inside_
  the browser (via WebAssembly)
  - meaning that unlike CodeSandbox and repl.it, their platform doesn't
    need to spin up and connect to a container on the backend
  - so it's much more efficient, performant, and cost-effective
  - and, importantly, it means you don't need an account to get started
    with a Node project; you only need an account to save your work etc
    - this makes a noticeable UX difference, since user funnels
      generally decrease the more steps you take (especially a larger
      one like creating an account)
      - and we want reproductions to be as easy as possible to create
        (so that people actually create them), so optimizing this flow
        is important
  - that being said, CodeSandbox and repl.it have much stronger OSS
    presences and have open-sourced most of their core technology
    - and Rollup and rollup/plugins use repl.it for reproductions:
      https://replit.com/@rollup/rollup-plugin-repro
    - so wanted to use those, but the UX difference was pretty
      significant
    - repl.it also didn't have as good a DX IMO

- have already made several reproductions of issues using this
  environment as well, so can confirm that it works well!

- StackBlitz: https://stackblitz.com/edit/rpt2-repro
- GitHub: https://github.com/agilgur5/rpt2-repro

.github/issue_template.md

@@ -16,7 +16,7 @@
       Rollup plugin order matters, so if there is a mismatch here, that could be the cause of your issue.
     -->
 
-1. Can you create a [minimal example](https://stackoverflow.com/help/minimal-reproducible-example) that reproduces this behavior?
+1. Can you create a [minimal example](https://stackoverflow.com/help/minimal-reproducible-example) that reproduces this behavior? Preferably, use [this environment](https://stackblitz.com/edit/rpt2-repro) for your reproduction
     <!--
       Minimal reproductions help us find the root cause of an issue much more expediently than trying to interpret and disentangle a complicated repo.
       The process of creating a minimal reproduction also often helps users find a misconfiguration in their code.