Update docs to replace middleware

[amenk]

Recent Laravel version require something like

])->replace([
    \Illuminate\Session\SessionServiceProvider::class => \iMi\LaravelTransSid\SessionServiceProvider::class,

to replace the middleware

[ahmed00227]

This method is not supported for replacing middleware rather only supported when you arr changing a service provider from default to a custom one

[amenk]

Interesting, what would you suggest?