Editing README for Simpl-SDK

[sangcu]

@thiennn several my ideas to build simpl-cli (a part of simpl-sdk)

[thiennn]

I think the roadmap should be:

• Make SimplCommerce module can be plug and play: register js, css file, menu item, run database script

• Implement enable/disable modules feature

• Build simpl CLI, first simpl publish, then others.

[sangcu]

@thiennn so we can add the roadmap detail for implementing into the wiki page. That would be the excellent place for people to understand under the hood and helping to contribute.

In the README file, it's only adding the expecting output of the SDK should be.
I'm considering you suggest simpl publish vs simpl deploy, the term simpl publish make sense then.