change URL

Change URL from developer.mbed.org to os.mbed.com
diff --git a/README.md b/README.md
index 378db1d..788c778 100644
--- a/README.md
+++ b/README.md
@@ -176,7 +176,7 @@
 -   We would ask that contributions conform to [our coding standards](https://tls.mbed.org/kb/development/mbedtls-coding-standards), and that contributions should be fully tested before submission.
 -   As with any open source project, contributions will be reviewed by the project team and community and may need some modifications to be accepted.
 
-To accept the Contributor’s Licence Agreement (CLA), individual contributors can do this by creating an Mbed account and [accepting the online agreement here with a click through](https://developer.mbed.org/contributor_agreement/). Alternatively, for contributions from corporations, or those that do not wish to create an Mbed account, a slightly different agreement can be found [here](https://www.mbed.com/en/about-mbed/contributor-license-agreements/). This agreement should be signed and returned to Arm as described in the instructions given.
+To accept the Contributor’s Licence Agreement (CLA), individual contributors can do this by creating an Mbed account and [accepting the online agreement here with a click through](https://os.mbed.com/contributor_agreement/). Alternatively, for contributions from corporations, or those that do not wish to create an Mbed account, a slightly different agreement can be found [here](https://www.mbed.com/en/about-mbed/contributor-license-agreements/). This agreement should be signed and returned to Arm as described in the instructions given.
 
 ### Making a Contribution