Improved Documentation Request

**Is your feature request related to a problem? Please describe.**
When a user starts out implementing Hive, the documentation is incomplete, particularly if the user wants to use the hive_generator. Too much prior knowledge is assumed of users.

**Describe the solution you'd like**
I'd just propose that here: https://docs.hivedb.dev/#/custom-objects/generate_adapter
Step One should reiterate the dependencies as listed here: https://docs.hivedb.dev/#/README
1-2 become 2-3
#4 needs to detail including part "...." in the model file user is employing;
#5 Then is the build_runner command - optimally with some explanation of what's happening here.
#6 Register the adapter.

That's all, thanks for the great plugin.

**Describe alternatives you've considered**
A clear and concise description of any alternative solutions or features you've considered.

**Version**
- Platform: iOS, Android, Mac, Windows, Linux, Web
- Flutter version: [e.g. 1.5.4]
- Hive version: [e.g. 0.5.0]