Clean up duplicate section in Cast documentation

[benley]

Description:

It looks like this was introduced accidentally by some kind of glitch, because #10339 appears to have been merged twice: 48f38a5 added the section, followed by 0c2c8f8 on the same branch.

Pull request in home-assistant (if applicable): n/a

Checklist:

• Branch: next is for changes and new documentation that will go public with the next Home Assistant release. Fixes, changes and adjustments for the current release should be created against current.
• The documentation follows the standards.

[frenck]

Hey @benley!

Thank you for the PR. Since this change has no dependency to an upcoming release (it has no parent PR that is pending release in our codebase), but a change to our documentation of or current release; this PR should target the current branch.

Please change the target branch of this PR to the current branch and rebase your PR if needed.

[emontnemery]

The "Advanced use" section is also duplicated, one is talking about Advanced use of the "Home Assistant Cast" feature, the other is talking about manually configuring chromecasts.

[frenck]

A small and friendly notification.

@benley, Are you planning on moving forward on this PR?
I didn't see any activity recently, while there are still things to do. I hope you consider picking it up soon! 👍

[benley]

Ah sorry, I lost track of the notification for this PR. I'll get it cleaned up for you.

[benley]

Fixed, I think.

[frenck]

Thanks, @benley! 👍

Happy Hacktoberfest 🎉