[docs] Add example with switch dark/light mode

• I have searched the issues of this repository and believe that this is not a duplicate.

Summary 💡

A basic template is needed that focuses on providing a solution or guide to developers on how to switch between dark/light mode. The idea is to be able to deliver a richer documentation in content of this feature.

Motivation 🔦

The motivation behind this is to be able to quickly provide developers with a solution to the question, How do I change the dark/light mode? Although there are examples on the internet, I think that a guide should come directly from the documentation, from how to set the ThemeProvider to how to switch between both modes.

Also in the documents I think that more help or information should be provided regarding the dark mode, the idea is to get the most out of this feature so used and demanded today.

[sohamsshah]

Thanks. Will look into this 😃

[sohamsshah]

@vicasas @oliviertassinari This looks a good issue to work on. Would love to be assigned for this task. Any suggestions or references I can refer for working for this? Thanks 😃