Fix linode example in Other S3-compatible Object Storages providers #2629

The Linode example in the Other S3-compatible Object Storages providers section of the docs specifies to use the following:

    destinationPath: "<destination path here>"
    endpointURL: "https://bucket.us-east1.linodeobjects.com"

However according to the Linode docs the endpointURL should specify the region and not the bucket.

The example should actually be:

    destinationPath: "s3://bucket"
    endpointURL: "https://us-east1.linodeobjects.com"

Interestingly, if the example in the docs is followed and the bucket URL is used as the value for endpointURL, the resulting behaviour is not outright failure and appears to be undefined. However, as demonstrated in both #1313 and EnterpriseDB/barman#835 this undefined behaviour makes debugging quite time consuming.