Improve documentation - with examples

Here are some confusing parts (hope this helps)


- `alpha` - is alpha `0-255` or `0-1` (or does it vary by space? - it should not be)
- what is values from rgba? 255 or 1?
- does hex color / named color input results a rgb space output?

These are missing on docs.

Nothing critical, just docuemntation improvements.