docs: add Parcel & MDX integration manual

[TechQuery]

📖 Description

add Integration Manual for:

1. Parcel: https://parceljs.org/
2. MDX: https://mdxjs.com/

✅ Checklist

General

• [x] I have included a change request file using $ npm run change
• [ ] I have added tests for my changes.
• [x] I have tested my changes.
• [x] I have updated the project documentation to reflect my changes.
• [x] I have read the CONTRIBUTING documentation and followed the standards for this project.

[TechQuery]

@microsoft-github-policy-service agree company="idea2app.cn"

[janechu]

Hi @TechQuery, a lot has changed since we published the 2.0.0 version of @microsoft/fast-element a few weeks ago, in our updated documentation we've streamlined things to be a single page, see https://fast.design/docs/integrations.

If you want to add any special configuration options you can add them on that page, or if using Parcel and MDX works well out of the box, feel free to just pop them on the list!

One of the reasons we've gone in this direction is to mitigate the overhead of keeping docs up to date.