Document Microsoft OneLake support

[kevinjqliu]

Context: #416 (comment)

Document support for OneLake, including

• OneLake Blob endpoint, onelake.blob.fabric.microsoft.com. (Azure Blob Storage -compatible)
• OneLake DFS endpoint, onelake.dfs.fabric.microsoft.com. (Azure Data Lake Storage -compatible)

Related issues:

• Support for MS Fabric OneLake #416
• Support For Microsoft OneLake dfs.fabric.microsoft.com #486
• Support DataLakeServiceClient for Azure Gen 2 Storage #401
• feat: add onelake support #513

[kevinjqliu]

#513 (comment)

OneLake blob endpoint is supported
OneLake dfs endpoint is not yet supported, blocked on #401

[kyleknap]

This makes sense to me to at least document how to use OneLake with adlfs and the current limitations.