Include link for full code for examples used in documentation

[johnpatrick254]

I'm currently learning Plate, however, it's difficult to understand how certain features work because the examples provided use dependencies that aren't installable using package managers, for example the toggle component documentation has a lot of important logic that cant be accessed because they are imported from @/lib folder. Including the full code will make it easier for beginners like me to understand some concepts faster https://platejs.org/docs/toggle#createtoggleplugin