Checkbox prop "partial" isn't HTML compliant

[lucasecdb]

Describe the bug
The prop partial in the Checkbox component doesn't respect HTML's specification.

To Reproduce

Steps to reproduce the behavior:

1. Go to Styleguide Checkbox's docs
2. Inspect the "partial" checkbox and store the input element reference to use in the console.
3. See the value of the property indeterminate of the input element.

Expected behavior

To have the indeterminate property of the input element set to true.

Screenshots

The temp0 variable is a reference to the second checkbox input's.

Additional context

Documentation.

[lucasecdb]

can we also rename this prop to indeterminate? so it's more "aligned" with the HTML spec

[emersonlaurentino]

@lucasecdb good catch, i will fix it!