Restyle Adding documentation for DataSource NewRelic

[restyled-io]

A duplicate of #638 with additional commits that automatically address
incorrect style, created by Restyled.

⚠️ Even though this PR is not a Fork, it contains outside contributions.
Please review accordingly.

Since the original Pull Request was opened as a fork in a contributor's
repository, we are unable to create a Pull Request branching from it with only
the style fixes.

The following Restylers made fixes:

• prettier-markdown

To incorporate these changes, you can either:

1. Merge this Pull Request instead of the original, or

2. Ask your contributor to locally incorporate these commits and push them to
   the original Pull Request

   Expand for example instructions

   ```console
   git remote add upstream https://github.com/getredash/website.git
   git fetch upstream pull/<this PR number>/head
   git merge --ff-only FETCH_HEAD
   git push
   ```
   

NOTE: As work continues on the original Pull Request, this process will
re-run and update (force-push) this Pull Request with updated style fixes as
necessary. If the style is fixed manually at any point (i.e. this process finds
no fixes to make), this Pull Request will be closed automatically.

Sorry if this was unexpected. To disable it, see our documentation.

[github-actions]

Images automagically compressed by Calibre's image-actions ✨

Compression reduced images by 44.9%, saving 41.21 KB.

Filename	Before	After	Improvement	Visual comparison
static/assets/images/docs/gitbook/newrelic-setup.png	91.86 KB	50.66 KB	-44.9%	View diff

385 images did not require optimisation.

Update required: Update image-actions configuration to the latest version before 1/1/21. See README for instructions.