[INTERNAL] README: Link to npm packages instead of bower repositories

https://github.com/openui5?query=packaged- lists the (to be deprecated)
repositories used by bower.

Also add a link to "What is npm?" page to help people getting started

Change-Id: I2fc2ba5cb864928ad3a8b79da4db722919b2b5cd

README.md

@@ -21,16 +21,16 @@ Get it!
 Go to the [download page](http://openui5.org/download.html) and get the complete UI5 runtime
 and the UI5 SDK containing the documentation and many example apps as well as the complete runtime.
 
-You can also consume [each OpenUI5 library](https://github.com/openui5?query=packaged-) individually via [npm](https://www.npmjs.com/package/@openui5/sap.ui.core), for example:
+You can also consume [every OpenUI5 library](https://www.npmjs.com/org/openui5) individually via [npm](https://docs.npmjs.com/getting-started/what-is-npm), for example:
 ```sh
-npm install @openui5/sap.ui.core @openui5/sap.m [...]
+npm install @openui5/sap.ui.core @openui5/sap.m @openui5/themelib_sap_belize [...]
 ```
 
 The UI5 distribution via Bower is stopped with 1.60+, as Bower itself is now [deprecated](https://github.com/bower/bower/issues/2298).
 
-⚠️ **Note**: Contrary to the bower releases, the npm releases do not contain library preload builds. The npm packages only contain the raw source files for the OpenUI5 libraries.
+⚠️ **Note**: Contrary to the bower releases, the npm releases do not contain library preload files. The npm packages only contain the raw source files of the OpenUI5 libraries.
 
-Preload packages for components and libraries can be build with the [UI5 tooling](https://sap.github.io/ui5-tooling/).
+Preload packages for components and libraries can be built using the [UI5 Build and Development Tooling](https://github.com/SAP/ui5-tooling).
 
 See also: [CLI guideline](https://github.com/SAP/ui5-cli#cli-usage)