feat(tvix/castore/blob): document missing objectstore+*:// URL

Change-Id: I3cbc75e636efd467ddda7fc3c3c8f19ad42204ee
Reviewed-on: https://cl.tvl.fyi/c/depot/+/11206
Autosubmit: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI
Reviewed-by: raitobezarius <tvl@lahfa.xyz>

tvix/castore/src/blobservice/from_addr.rs

@@ -12,6 +12,7 @@ use super::{
 /// - `memory://` ([MemoryBlobService])
 /// - `sled://` ([SledBlobService])
 /// - `grpc+*://` ([GRPCBlobService])
+/// - `objectstore+*://` ([ObjectStoreBlobService])
 ///
 /// See their `from_url` methods for more details about their syntax.
 pub async fn from_addr(uri: &str) -> Result<Box<dyn BlobService>, crate::Error> {