man/io_uring_register.2: Add documentation on IORING_REGISTER_FILES_SKIP

Add documentation for IORING_REGISTER_FILES_SKIP feature in
IORING_REGISTER_FILES_UPDATE.

Signed-off-by: Noah Goldstein <goldstein.w.n@gmail.com>
diff --git a/man/io_uring_register.2 b/man/io_uring_register.2
index 225e461..6636b6e 100644
--- a/man/io_uring_register.2
+++ b/man/io_uring_register.2
@@ -144,6 +144,7 @@
 ones, either turning a sparse entry (one where fd is equal to -1) into a
 real one, removing an existing entry (new one is set to -1), or replacing
 an existing entry with a new existing entry.
+
 .I arg
 must contain a pointer to a struct io_uring_files_update, which contains
 an offset on which to start the update, and an array of file descriptors to
@@ -152,6 +153,12 @@
 must contain the number of descriptors in the passed in array. Available
 since 5.5.
 
+File descriptors can be skipped if they are set to
+.B IORING_REGISTER_FILES_SKIP.
+Skipping an fd will not touch the file assosiated with the previous
+fd at that index. Available since 5.12.
+
+
 .TP
 .B IORING_UNREGISTER_FILES
 This operation requires no argument, and