Update contributing guidelines and add documentation link

Added a link to the contributing documentation and updated the General Contribution Flow section.

Signed-off-by: Mericio <218162243+simihablo@users.noreply.github.com>

Author: simihablo

CONTRIBUTING.md

@@ -1,15 +1,17 @@
 # <a name="contributing">Contributing Overview</a>
 Please do! Thanks for your help improving the project! :balloon:
 
+## --> See https://docs.layer5.io/contributing <--
+
 All contributors are welcome. Please see the [newcomers welcome guide](https://layer5.io/community/newcomers) for how, where and why to contribute. This project is community-built and welcomes collaboration. Contributors are expected to adhere to our [Code of Conduct](CODE_OF_CONDUCT.md).
 
 Not sure where to start? First, see the [newcomers welcome guide](https://layer5.io/community/newcomers). Grab an open issue with the [help-wanted label](../../labels/help%20wanted) and jump in. Join the [Slack account](http://slack.layer5.io) and engage in conversation. Create a [new issue](/../../issues/new/choose) if needed.  All [pull requests](/../../pulls) should reference an open [issue](/../../issues). Include keywords in your pull request descriptions, as well as commit messages, to [automatically close issues in GitHub](https://help.github.com/en/github/managing-your-work-on-github/closing-issues-using-keywords).
 
 **Sections**
-- <a name="contributing">General Contribution Flow</a>
-  - <a href="#prerequisites">Prerequisites</a>
-  - <a href="#set-up-your-local-development-environment">Set up your Local Development Environment</a>
-  - <a href="#commit-signing">Developer Certificate of Origin</a>
+<a name="contributing">General Contribution Flow</a>
+- <a href="#prerequisites">Prerequisites</a>
+- <a href="#set-up-your-local-development-environment">Set up your Local Development Environment</a>
+- <a href="#commit-signing">Developer Certificate of Origin</a>
 
 Relevant coding style guidelines are the Go Code Review Comments and the Formatting and style section of Peter Bourgon's Go: Best Practices for Production Environments.