Motivation
It is a common practice to have the CONTRIBUTING.md file with info on how to start contributing to the project.

Modifications
CONTRIBUTING.md was added to the project with the link to the official Apache Pulsar page.

*Motivation*

The current helm chart is lacking documentation. This pull request aims to add documentation.

*Changes*

- Update Helm chart documentation
- Add a get-started section with Helm chart
- Remove the documentation of using yaml files.

Signed-off-by: Nxiaolong.ran <rxl@apache.org>
Signed-off-by: Nxiaolong.ran <rxl@apache.org>

Fixes #5787 

### Motivation

When we creating a K8S cluster on Minikube, due to the different versions of Minikube in the local environment, the installation fails on `--kubernetes-version=v1.10.5`.

### Modifications

- Remove the `--kubernetes-version=v1.10.5` in docs.

* [documentation][deploy] Update deployment instructions for deploying to Minikube

* Enable functions workers

* [documentation][deploy] Improve helm deployment script to deploy Pulsar to minikube

 ### Changes

- update the helm scripts: bookie/autorecovery/broker pods should wait until metadata is initialized
- disable `autoRecovery` on bookies since we start `AutoRecovery` in separate pods
- enable function worker on brokers
- provide a values file for minikube
- update documentation for using helm chart to deploy a cluster to minikube

* move the service type definition to values file

* Helm charts for deployment on GKE

* Repackaginh helm charts under deployment/kubernetes/helm

* Formatting licences

* Removing cloud specific values to enable more generic deployments