improve connection docs

[leogermani]

Changes proposed in this Pull Request:

• Improves docs for the connection package

Other information:

• Have you written new tests for your changes, if applicable?
• Have you checked the E2E test CI results, and verified that your changes do not break them?

Jetpack product discussion

p1660768531023429-slack-CBG1CP4EN

Does this pull request change what data or activity we track or use?

No

Testing instructions:

• Check the docs

[test-case-reminder]

Here are some suggested test cases for this PR.

Connection

• In-place connection with free plan
• In-place connection with paid plan
• In-place connection with product purchase
• Classic connection. Use Safari, or set a constant JETPACK_SHOULD_NOT_USE_CONNECTION_IFRAME to true
• Disconnect/reconnect connection
• Secondary user connection
• Connection on multisite

Verify that the changes are compatible with the plugins that use the connection package.

• WooCommerce Payments
• Jetpack Boost
• Previous versions of Jetpack

If you think that suggestions should be improved please edit the configuration file here. You can also modify/add test-suites to be used in the configuration file.

[github-actions]

Thank you for your PR!

When contributing to Jetpack, we have a few suggestions that can help us test and review your patch:

• ✅ Include a description of your PR changes.
  
• ✅ All commits were linted before commit.
  
• ✅ Add a "[Status]" label (In Progress, Needs Team Review, ...).
  
• ✅ Add testing instructions.
  
• ✅ Specify whether this PR includes any changes to data or privacy.
  
• ✅ Add changelog entries to affected projects
  

This comment will be updated as you work on your PR and make changes. If you think that some of those checks are not needed for your PR, please explain why you think so. Thanks for cooperation 🤖

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