Update readme (#206)

* Update readme

One proposition of change for the presentation, listing 6 cloud providers is already out of date as new cloud providers was added and will be added in future. 
I put a more generic sentence. So no need to update the readme each time a new provider is added.
I think that there's no need to list all providers as the badges just above list them.
I also added saas and programming I tried to be generic so here also no need to update the readme when adding new resources. 

I hope I didn't misspell words and my grammar is correct.

* Fix space

README.md

@@ -24,7 +24,7 @@
 
 **Diagram as Code**.
 
-Diagrams lets you draw the cloud system architecture **in Python code**. It was born for **prototyping** a new system architecture design without any design tools. You can also describe or visualize the existing system architecture as well. Diagrams currently supports six major providers: `AWS`, `Azure`, `GCP`, `Kubernetes`, `Alibaba Cloud` and `Oracle Cloud`.  It now also supports `On-Premise` nodes.
+Diagrams lets you draw the cloud system architecture **in Python code**. It was born for **prototyping** a new system architecture design without any design tools. You can also describe or visualize the existing system architecture as well. Diagrams currently supports main major providers including: `AWS`, `Azure`, `GCP`, `Kubernetes`, `Alibaba Cloud`, `Oracle Cloud` etc... It also supports `On-Premise` nodes, `SaaS` and major `Programming` frameworks and languages.
 
 **Diagram as Code** also allows you to **track** the architecture diagram changes in any **version control** system.