Update contributing.md to new CLA location

This commit updates contributing.md to point to the ARM website
for downloading copies of the Contribution License Agreement (CLA).
It is no longer necessary to email ARM for these.

Change-Id: Iaf58680631a626f26827577709ac5471e3b84566
diff --git a/contributing.md b/contributing.md
index 01a90f8..e5a1eee 100644
--- a/contributing.md
+++ b/contributing.md
@@ -7,9 +7,8 @@
 Individuals who want to contribute their own work must sign and return an
 Individual CLA. Companies that want to contribute must sign and return a
 Corporate CLA if their employees' intellectual property has been assigned to
-the employer. Copies of the CLAs are available on request from
-[cla-submissions@arm.com]. They will be available from http://www.arm.com in
-due course.
+the employer. Copies of the CLAs are available from the [contributing page] of
+the ARM website.
 
 For this project, ARM also requires the GitHub account name(s) associated with
 each individual contributor or the designated employees of corporate
@@ -106,7 +105,7 @@
 [Porting Guide]:                        ./docs/porting-guide.md
 [Acknowledgements]:                     ./acknowledgements.md "Contributor acknowledgements"
 
-[cla-submissions@arm.com]:      mailto:cla-submissions@arm.com
+[contributing page]:            http://www.arm.com/community/open-source-contributing.php
 [GitHub account]:               https://github.com/signup/free
 [Fork]:                         https://help.github.com/articles/fork-a-repo
 [issue tracking repository]:    https://github.com/ARM-software/tf-issues