Add generation documentation (#858)
Add generation documentation (#858)

* Add generation documentation

* Add how to generate a single service

* Create new doc file

* Renamed sections and changed its order

* Fixed command

* More comments

curoverse/azure-sdk-for-go,curoverse/azure-sdk-for-go,marstr/azure-sdk-for-go,marstr/azure-sdk-for-go,marstr/azure-sdk-for-go,Azure/azure-sdk-for-go,Azure/azure-sdk-for-go,Azure/azure-sdk-for-go,Azure/azure-sdk-for-go