docs: sort library doc index alphabetically

- Changed library documentation index alphabetically

Signed-off-by: Nitin Saxena <nsaxena@marvell.com>
Change-Id: I199d32c0938c46cb69509a63e7305035b00965a7
Reviewed-on: https://sj1git1.cavium.com/c/IP/SW/dataplane/dpu-offload/+/134571
Reviewed-by: Jerin Jacob <jerinj@marvell.com>
Tested-by: Jerin Jacob <jerinj@marvell.com>

doc/guides/prog_guide/index.rst

@@ -10,11 +10,11 @@ Programmer's Guide
 
     common
     dma_lib
+    flow
+    netlink_lib
     pem_lib
+    port_group
+    port_queue_group
     vfio_lib
     virtio_lib
     virtio_net_lib
-    flow
-    port_group
-    port_queue_group
-    netlink_lib