[docs] Use pointer cursor for Codesandbox external "link"

[LukasTy]

Given that we discussed that only external links should use the pointer cursor, I've added this style to the CodeSandbox "link".

[pkg-pr-new]

vite-css-base-ui-example

pnpm add https://pkg.pr.new/mui/base-ui/@base-ui-components/react@2865

pnpm add https://pkg.pr.new/mui/base-ui/@base-ui-components/utils@2865

commit: ff5259e

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[mui-bot]

Bundle size report

Bundle	Parsed size	Gzip size
@base-ui-components/react	0B(0.00%)	0B(0.00%)

Details of bundle changes

[atomiks]

A bit of an ambiguous case since you can't right click on it to reveal native <a> related options 🤔

[LukasTy]

A bit of an ambiguous case since you can't right click on it to reveal native <a> related options 🤔

Yeah. That's true.
We can keep it as is, If there is an agreement that this is a blocker for signalling this as a link.
But on the other hand, it has an anchor icon in the text. 🤔 🤷