add Gitpod doc

[DukeManh]

Fixes #2429

This adds the Gitpod doc for development on Gitpod.

Issue This PR Addresses

Type of Change

• Bugfix: Change which fixes an issue
• New Feature: Change which adds functionality
• Documentation Update: Change which improves documentation
• UI: Change which improves UI

Description

Checklist

• Quality: This PR builds and passes our npm test and works locally
• Tests: This PR includes thorough tests or an explanation of why it does not
• Screenshots: This PR includes screenshots or GIFs of the changes made or an explanation of why it does not (if applicable)
• Documentation: This PR includes updated/added documentation to user exposed functionality or configuration variables are added/changed or an explanation of why it does not(if applicable)

[gitpod-io]

[humphd]

This is excellent to have

[DukeManh]

@humphd Can you re-review please. cc @cindyledev.

[humphd]

Amazing. We should find a student in the class who wants to develop something on Telescope to use this, and test it out to see if it's missing anything or unclear.