Fix doc inputs

[akiyamaSM]

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Summary

This PR fixes/implements the following bugs/features

• [ ] #issue1
• [ ] #issue2
• [ ] #Feature1
• [ ] #Feature2
• [ ] Breaking changes

Explain the motivation for making this change. What existing problem does the pull request solve?

Requirements

Make sure these boxes are checked:

• [ ] link to an issue
• [ ] tests are updated (added/changed/removed)
• [ ] tests run successfully (local)
• [ ] tests run successfully (TravisCI)
• [ ] please follow this styleguide for this pr title

[akiyamaSM]

@Component({
  selector: 'app-root',
  template: `
   <div class="app">
      <counter [init]="initialCount"></counter>
    </div>
  `
})
export class AppComponent {
  initialCount: number = 10;
}

you can't bind a value directly, if so you need to remove the []