Documentation: update missing index files in block/00-INDEX

Update missing index files in block/00-INDEX.
Signed-off-by: NWei Fang <fangwei1@huawei.com>
Signed-off-by: NJonathan Corbet <corbet@lwn.net>

Documentation/block/00-INDEX

@@ -2,6 +2,8 @@
 	- This file
 biodoc.txt
 	- Notes on the Generic Block Layer Rewrite in Linux 2.5
+biovecs.txt
+	- Immutable biovecs and biovec iterators
 capability.txt
 	- Generic Block Device Capability (/sys/block/<device>/capability)
 cfq-iosched.txt
@@ -14,6 +16,8 @@ deadline-iosched.txt
 	- Deadline IO scheduler tunables
 ioprio.txt
 	- Block io priorities (in CFQ scheduler)
+pr.txt
+	- Block layer support for Persistent Reservations
 null_blk.txt
 	- Null block for block-layer benchmarking.
 queue-sysfs.txt