adicionando um exemplo ao Fixed-Effects

[LPecht]

Matheus, no parágrafo

https://matheusfacure.github.io/python-causality-handbook/14-Panel-Data-and-Fixed-Effects.html#time-effects

". To give a more concrete example, suppose that marriage is increasing with time."

vc poderia exemplificar, com

". To give a more concrete example, suppose that marriage is increasing with time due to popularity of relationship apps, such as Tinder and Happn."