docs: update for default target change

[sapphi-red]

Description

• After feat!: relative base #7644, it is not necessary to set build.target to use import.meta.url.
• The description on https://vitejs.dev/config/#build-target was left stale after refactor!: esbuild 0.11 upgrade, remove dynamic-import-polyfill #2976.
• Update docs about default target

Additional context

There is a lot of places written about default target.
It might be better to mention it in detail at one place and make others a link to it.

• https://vitejs.dev/guide/#browser-support
• https://vitejs.dev/guide/build.html#browser-compatibility
• https://vitejs.dev/config/#build-target

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What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

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• Read the Contributing Guidelines.
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