add more documentation to auth and file management

[matiasrebori]

Description

Recently I needed to use Google Drive with Python so this library was very useful but I needed more help for my uses cases that arent the simplest or common, I want to extend the documentation to make more easy its use for future users.

What has been done

• Oauth: with google service account
• File management: Get files by complex queries with q parameters
• File management: Upload data as bytes in memory buffer
• File management: Upload file to specific folder

Note

See #230 for more insight on the motivation for this.