doc: Add the link for the documentation of the .its

Provide the link for the .its related documentation for Arria10.

Signed-off-by: Jit Loon Lim <jit.loon.lim@intel.com>
diff --git a/doc/device-tree-bindings/fpga/altera-socfpga-a10-fpga-mgr.txt b/doc/device-tree-bindings/fpga/altera-socfpga-a10-fpga-mgr.txt
index da210bf..1381bdc 100644
--- a/doc/device-tree-bindings/fpga/altera-socfpga-a10-fpga-mgr.txt
+++ b/doc/device-tree-bindings/fpga/altera-socfpga-a10-fpga-mgr.txt
@@ -41,3 +41,6 @@
 		resets = <&rst FPGAMGR_RESET>;
 		altr,bitstream = "fit_spl_fpga.itb";
 	};
+
+- The .its related documentations can be found here
+	- Appendix - Reducing Arria 10 Fabric Configuration Time - https://rocketboards.org/foswiki/Documentation/BuildingBootloaderCycloneVAndArria10