docs: add GA conf to config

[villebro]

SUMMARY

A recent migration of the docs site to Docusaurus in #17411 lost Google Analytics tracking. Here we add the same GA confs that were introduced in #11613 by leveraging the plugin-google-analytics plugin that's included in the preset-classic that's already in use. In addition, Docusaurus is bumped to the latest version as the configuration mechanism changed recently (see facebook/docusaurus#5832 which was included in the 2.0.0-beta.10 release). A missing license property is added to the package.json file of the docs package.

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

The site looks the same as before:

TESTING INSTRUCTIONS

Make sure the docs site builds correctly and looks correct when run locally:

1. cd docs
2. yarn install
3. yarn build
4. yarn start

ADDITIONAL INFORMATION

• Has associated issue:
• Required feature flags:
• Changes UI
• Includes DB Migration (follow approval process in SIP-59)
  • Migration is atomic, supports rollback & is backwards-compatible
  • Confirm DB migration upgrade and downgrade tested
  • Runtime estimates and downtime expectations provided
• Introduces new feature or API
• Removes existing feature or API

[geido]

Thanks!