[5.4] Add kebab case to Str with kebab_case helper

[calebporzio]

It seems to be a convention to "kebab-case" blade view names. Therefore, a kebab method would be helpful for instances such as the following:

I want to "polymorphically" change views based on different notification types.

<a href="#">
    @include('notifications.' . snake_case(class_basename($notification->type), '-'))
</a>

Could become:

<a href="#">
    @include('notifications.' . kebab_case(class_basename($notification->type)))
</a>

Thanks for the hard work and time put into reviewing PRs like these.

[bbashy]

Can't you just use str_slug()?

[calebporzio]

Cool, didn't know that. Maybe that's reason in itself it needs to be in there...?

[bbashy]

It's fine having a separate helper but assumed you knew about str_slug() 😄

[vpratfr]

@calebporzio You should update the docs too, that helper function is not referenced in the corresponding chapter.