Improve `title` attribute support in `<YouTube>` and document it

[delucis]

• Uses title to set data-title at build time so it displays before the custom element is defined
• Documents that this attribute exists.

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Latest commit: ba37f0e58ace07915dda852501f8f312f2e83e12

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This PR includes changesets to release 1 package

| Name | Type | | ------------------------------------ | ----- | | @astro-community/astro-embed-youtube | Patch |

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