add docs and annotations for colors

[Bruno125]

What are you trying to accomplish?

• Add docs to the new public Color classes
• Add annotations (@ColorInt and @ColorRes) for a more robust value enforcement (int is too generic)

Before you deploy

• I have added tests to support my implementation
• I have read and agree with
  the contributing documentation
• I have read and agree with
  the code of conduct documentation
• I have updated any documentation related to these changes.
• I have updated the README (if applicable).

[kiftio]

💯

[kiftio]

One more semi-related thing. Do you think we should also make these public instaed of internal?

public data class Automatic(
        internal var lightColors: Colors = defaultLightColors,
        internal var darkColors: Colors = defaultDarkColors