packfile-uri.txt: fix blobPackfileUri description

Fix the 'uploadpack.blobPackfileUri' description in packfile-uri.txt
and the correct format also can be seen in t5702.

Signed-off-by: Teng Long <dyroneteng@gmail.com>
Reviewed-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/technical/packfile-uri.txt

@@ -35,13 +35,14 @@ include some sort of non-trivial implementation in the Minimum Viable Product,
 at least so that we can test the client.
 
 This is the implementation: a feature, marked experimental, that allows the
-server to be configured by one or more `uploadpack.blobPackfileUri=<sha1>
-<uri>` entries. Whenever the list of objects to be sent is assembled, all such
-blobs are excluded, replaced with URIs. As noted in "Future work" below, the
-server can evolve in the future to support excluding other objects (or other
-implementations of servers could be made that support excluding other objects)
-without needing a protocol change, so clients should not expect that packfiles
-downloaded in this way only contain single blobs.
+server to be configured by one or more `uploadpack.blobPackfileUri=
+<object-hash> <pack-hash> <uri>` entries. Whenever the list of objects to be
+sent is assembled, all such blobs are excluded, replaced with URIs. As noted
+in "Future work" below, the server can evolve in the future to support
+excluding other objects (or other implementations of servers could be made
+that support excluding other objects) without needing a protocol change, so
+clients should not expect that packfiles downloaded in this way only contain
+single blobs.
 
 Client design
 -------------