document what `public` means for files

[shazron]

public here does not mean accessible to the whole public internet in general.

public means you don’t need any credentials to access the file:

1. you can access a file across runtime actions only (internalUrl or url property below)
2. you can access the file publicly on the Internet if you use the CDN link (url property below)

> await files.write('public/test', 'i am public')
11
> await files.getProperties('public/test')
{
  name: 'public/test',
  creationTime: 2023-11-10T09:29:02.000Z,
  lastModified: 2023-11-10T09:29:02.000Z,
  etag: '"0x9GBE1CF7A26B67A"',
  contentLength: 11,
  contentType: 'application/octet-stream',
  isDirectory: false,
  isPublic: true,
  url: 'https://my-cdn-domain.net/example-not-working-container-id-public/public/test',
  internalUrl: 'https://my-blob-storage.net/example-not-working-container-id-public/public/test'
}

Note url vs internalUrl (valid only when isPublic is true in this case). Direct access to the blob storage is restricted.

[aiojbot]

JIRA issue created: https://jira.corp.adobe.com/browse/ACNA-2628