add contributing guide to readme

Author: edenlightning

README.md

@@ -14,6 +14,7 @@ ______________________________________________________________________
   <a href="https://pytorch-lightning.readthedocs.io/en/stable/">Docs</a> •
   <a href="#examples">Examples</a> •
   <a href="#community">Community</a> •
+  <a href="https://pytorch-lightning.readthedocs.io/en/stable/generated/CONTRIBUTING.html">Contribute</a> •
   <a href="#license">License</a>
 </p>
 
@@ -406,7 +407,7 @@ The lightning community is maintained by
 - [10+ core contributors](https://pytorch-lightning.readthedocs.io/en/latest/governance.html) who are all a mix of professional engineers, Research Scientists, and Ph.D. students from top AI labs.
 - 590+ active community contributors.
 
-Want to help us build Lightning and reduce boilerplate for thousands of researchers? [Learn how to make your first contribution here](https://devblog.pytorchlightning.ai/quick-contribution-guide-86d977171b3a)
+Want to help us build Lightning and reduce boilerplate for thousands of researchers? [Learn how to make your first contribution here](https://pytorch-lightning.readthedocs.io/en/stable/generated/CONTRIBUTING.html)
 
 Lightning is also part of the [PyTorch ecosystem](https://pytorch.org/ecosystem/) which requires projects to have solid testing, documentation and support.