Rocket.Chat/.github/PULL_REQUEST_TEMPLATE.md

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<!-- Your Pull Request name should start with one of the following tags
  feat: Adding a new feature
  refactor: A code change that doesn't change behavior (it doesn't add anything and doesn't fix anything)
  fix: For bug fixes that affect the end-user
  chore: For small tasks
  docs: For documentation
  ci: For updating CI configuration
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  i18n: For updating any translations
  regression: Issues created/reported/fixed during the development phase. kind of problem that never existed in production and that we don't need to list in a changelog for the end user
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<!-- Checklist!!! If you're unsure about any of them, don't hesitate to ask. We're here to help! This is simply a reminder of what we are going to look for before merging your code. 
  - I have read the Contributing Guide - https://github.com/RocketChat/Rocket.Chat/blob/develop/.github/CONTRIBUTING.md#contributing-to-rocketchat doc
  - I have signed the CLA - https://cla-assistant.io/RocketChat/Rocket.Chat
  - Lint and unit tests pass locally with my changes
  - I have added tests that prove my fix is effective or that my feature works (if applicable)
  - I have added necessary documentation (if applicable)
  - Any dependent changes have been merged and published in downstream modules
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## Proposed changes (including videos or screenshots)
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  Describe the big picture of your changes here to communicate to the maintainers why we should accept this pull request.
  If it fixes a bug or resolves a feature request, be sure to link to that issue below.
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## Issue(s)
<!-- Link the issues being closed by or related to this PR. For example, you can use #594 if this PR closes issue number 594 -->

## Steps to test or reproduce
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## Further comments
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