Add hello world tutorial

[dragosgd]

Purpose

Add hello world tutorial

Changes

-new hello world tutorial added

Checklist

• My code follows the style of this project.
• The code compiles without warnings.
• I have performed a self-review of the changes.
• I have documented my code, in particular the intent of the
  hard-to-understand areas.
• (If necessary) I have updated the CHANGELOG.

CLA acceptance

By submitting the contribution I accept the terms and conditions of the
Contributor License Agreement v1.0

• link: https://developers.concordium.com/CLAs/Contributor-License-Agreement-v1.0.pdf

• I accept the above linked CLA.

[it09]

Good start! left a couple of comments, mainly we need to add more explanations of what /why we do what we do :)

[dragosgd]

Good start! left a couple of comments, mainly we need to add more explanations of what /why we do what we do :)

You're right, I explained the entire process in more details and mentioned why methods were modified.

[it09]

Yay 🎉 Almost there!