Adds a description in example file

Comparison to native element
Adds a value="0"` example for
Adds a `max="0"` example
Fixes falsey attributes

It’s now possible to set min, max, value, step to 0.
Fixes #54, #51
Merge pull request #59 from andreruffert/falsey-min-max-value-step--fix

Falsey min, max, value, step, fix