update issue template (issue #502)

[Pandademic]

Make sure these boxes are checked before your pull request (PR) is ready to be reviewed and merged. Thanks!

• tests pass -- look for a green checkbox ✔️ a few minutes after opening your PR -- or run tests locally with rake test
• code is in uniquely-named feature branch and has no merge conflicts
• [ x] PR is descriptively titled
• PR body includes fixes #0000-style reference to original issue #
• ask @publiclab/reviewers for help, in a comment below
  Tested failed on nodejs 8 , but this is almost docs.
  This fixes Update the Issue Template. #502.

[welcome]

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[Pandademic]

@publiclab/reviewers , is this good?