Documentation Updates

[nhandyal]

Thanks for creating this crate! As I'm getting started, I'm noticing some errors / shortcomings in the documentation which I want to document here so it can be updated.

In READEME.md

The service account requires the permission devstorage.full_control

It doesn't look like this is a valid permission anymore.

In READEME.md
Example

// create a new Bucket
let new_bucket = NewBucket { name: "mybucket", ..Default::default() }
let bucket = Bucket::create(new_bucket).await?;
// upload a file to our new bucket
let content = b"Your file is now on google cloud storage!";
bucket.upload(content, "folder/filename.txt", "application/text").await?;

no method named upload found for struct cloud_storage::Bucket

In the features section of docs.rs

global-client -- This feature flag does not enable additional features.

However there are methods gated by this feature. Ex: Bucket::list

Missing permissions
Bucket::read requires the storage.buckets.get permission which is not mentioned in the README. This permission is not included in the Service Account Token Creator or Storage Object Admin roles.