Description

Updating description for Nested Scaffolds. The doc earlier didn't make it clear if we could use multiple scaffolds for multiple routes. Rather it mislead, making users think that there should only be one Scaffold for a whole MaterialApp, which is not the real intent.

Note: I had created a PR earlier (#64645) but because of an unintentional pull the branch got a lot of unintended changes.

Related Issues

Fixes #64136

Tests

Only documentation changed. No tests needed

Checklist

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• I updated/added relevant documentation (doc comments with ///).
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Breaking Change

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• Yes, this is a breaking change.