docs: fix broken link in signals/model

[hyundonmoon]

PR Checklist

Please check if your PR fulfills the following requirements:

• [ ] The commit message follows our guidelines: https://github.com/angular/angular/blob/main/CONTRIBUTING.md#commit
• [ ] Tests for the changes have been added (for bug fixes / features)
• [x] Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• [ ] Bugfix
• [ ] Feature
• [ ] Code style update (formatting, local variables)
• [ ] Refactoring (no functional changes, no api changes)
• [ ] Build related changes
• [ ] CI related changes
• [x] Documentation content changes
• [ ] angular.io application / infrastructure changes
• [ ] Other... Please describe:

What is the current behavior?

Clicking on the link to "standard inputs" at the bottom of the Model inputs page leads to the 404 page due to a broken link.

Issue Number: N/A

What is the new behavior?

Clicking on said link correctly navigates to the Signal inputs page.

Does this PR introduce a breaking change?

• [ ] Yes
• [x] No

Other information

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[JeanMeche]

Thank you for fixing the link, we appreciate this kind of contributions !

[dylhunn]

This PR was merged into the repository by commit b89c88c73bfd98fcda704a836f1943a6f7116a79.