"Further Help" section in Contributing Guide

[RichardChukwu]

This is part of https://github.com/open-telemetry/sig-contributor-experience/issues/31

The goal is to create a clear guide for first time contributors to contribute seamlessly to each otel repo with a consistent pattern for the contributing guide.

So far, the otel-lambda considering its a multi-lingual repo has all important info already stated in the template like Pre-requisites, Local Run/Build and testing needed in the collector file as stated in the CONTRIBUTING guide.

However, I noticed the otel-lambda slack channel has been archived, where can first time contributors go to seek help and assistance please, or is opening an issue the only way to do this on this repo?

I'm open to adding this info if I can get clarity on it please