Update the link to CLA in CONTRIBUTING.mdown

Summary:
The CLA link doesn't lead anywhere at the moment and I'm guessing it's out of date

![image](https://github.com/user-attachments/assets/d95f8b46-48f2-4ccf-a9bd-3a5ac49d07b4)

We can replace this link with an up-to-date one for CLA signatures (it was taken from Meta's neighboring opensource projects and is up-to-date)

X-link: facebook/facebook-java-business-sdk#469

Reviewed By: liliarizona

Differential Revision: D67467971

Pulled By: stcheng

fbshipit-source-id: 1ff530d99b416f08f937a63715c02ddccac47ad3

templates/java/CONTRIBUTING.mdown

@@ -2,14 +2,14 @@ Facebook welcomes contributions to our SDKs.
 
 All contributors must sign a CLA (contributor license agreement) here:
 
-  https://developers.facebook.com/opensource/cla
+  https://code.facebook.com/cla
 
 To contribute on behalf of your employer, sign the company CLA
 To contribute on behalf of yourself, sign the individual CLA
 
 All contributions:
 
-1/ MUST be be licensed using the Apache License, Version 2.0  
-2/ authors MAY retain copyright by adding their copyright notice to the appropriate flies 
+1/ MUST be be licensed using the Apache License, Version 2.0
+2/ authors MAY retain copyright by adding their copyright notice to the appropriate flies
 
 More information on the Apache License can be found here: http://www.apache.org/foundation/license-faq.html