Add BackBlaze Support to Docs

[bawahakim]

Thanks to @uzaysan, realized we could use BackBlaze instead of S3. Needed a bit of tinkering until I got it to work, but I figured it would be nice to have this in the read me. These are the settings I used to make it work :

const s3Adapter = new S3Adapter({
  bucket: process.env.S3_BUCKET,
  directAccess: true,
  baseUrl: process.env.S3_BASE_URL, // taken from BackBlaze, normally https://BUCKET.s3.REGION.backblazeb2.com
  baseUrlDirect: false,
  signatureVersion: 'v4',
  globalCacheControl: 'public, max-age=86400',
  region: 'us-west-000',
  s3overrides: {
    endpoint: process.env.S3_ENDPOINT, // check backblaze bucket endpoint
    accessKeyId: process.env.S3_ACCESS_KEY,
    secretAccessKey: process.env.S3_SECRET_KEY
  },
});

[mtrezza]

Thanks for suggesting.

Do you want to open a PR for this docs change?

On a general note, you may want to check for any compatibility issues when using AWS S3-emulating storage.

[mtrezza]

Closing via parse-community/docs#825