Update View Transitions Docs

[OliverSpeir]

📋 Suggested page

https://docs.astro.build/en/guides/view-transitions/

📋 General description or bullet points (if proposing new content)

Add "Removing <ViewTransitions/> Component section

• "What needs to change?"
• "What can I keep?"
• "How do I reuse my custom animations?"

Maybe add tracking of browser support, I personally will volunteer for keeping this updated

As of right now:

• Chrome and Edge support level 2
• Safari added level 1, I haven't found a good issue to track level 2
• Firefox has plans for level 1 in new couple months, Bugzilla