Update web custom component example in the docs

[carolinegoncalveszup]

What would you like to be added:
The custom component that is presented in the docs for android and iOS is the same, the ColorSelector (see https://docs.usebeagle.io/features/componentes/criando-seu-componente/android). The web example is a completely different one, a CustomText (https://docs.usebeagle.io/features/componentes/criando-seu-componente/web). The idea is to have all the examples the same, showing how it would be implemented for each platform.

Why is this needed:
To keep the doc consistent between the different platforms

[Tiagoperes]

Transferred to the docs repository.