Fixed the "touch target size" broken docs link.

[feinstein]

Description

Fixed the "touch target size" broken docs link.

Related Issues

#53792

Tests

I added the following tests:

No added tests as this was just a change on the docs.

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Breaking Change

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[fluttergithubbot]

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[HansMuller]

LGTM

[HansMuller]

Thanks for catching this! Will land when the build is green.

[feinstein]

:) my pleasure.