Docs: Align content of README from About chapter

Author: Michael Friedrich

README.md

@@ -16,25 +16,33 @@
 
 ## About
 
-[Icinga 2](https://icinga.com/products/icinga-2/) is a monitoring system which checks
+[Icinga](https://icinga.com/products/) is a monitoring system which checks
 the availability of your network resources, notifies users of outages, and generates
 performance data for reporting.
 
-Scalable and extensible, Icinga 2 can monitor large, complex environments across
+Scalable and extensible, Icinga can monitor large, complex environments across
 multiple locations.
 
-Icinga 2 as core requires [Icinga Web 2](https://icinga.com/products/icinga-web-2/)
-on top in your Icinga Stack.
+Icinga 2 is the monitoring server and requires [Icinga Web 2](https://icinga.com/products/)
+on top in your Icinga Stack. The [configuration](https://icinga.com/products/configuration/)
+can be easily managed with either the [Icinga Director](https://icinga.com/docs/director/latest/),
+config management tools or plain text within the [Icinga DSL](https://icinga.com/docs/icinga2/latest/doc/17-language-reference/).
 
 ![Icinga Dashboard](https://icinga.com/wp-content/uploads/2017/12/icingaweb2-2.5.0-dashboard.png)
 
 ## Installation
 
-For installing Icinga please check the [installation chapter](https://icinga.com/docs/icinga2/latest/doc/02-getting-started/)
-in the documentation.
+* [Installation](https://icinga.com/docs/icinga2/latest/doc/02-installation/)
+* [Monitoring Basics](https://icinga.com/docs/icinga2/latest/doc/03-monitoring-basics/)
+* [Configuration](https://icinga.com/docs/icinga2/latest/doc/04-configuration/)
+* [Distributed Monitoring](https://icinga.com/docs/icinga2/latest/doc/06-distributed-monitoring/)
+* [Addons, Integrations and Features](https://icinga.com/docs/icinga2/latest/doc/13-addons/)
+* [Troubleshooting](https://icinga.com/docs/icinga2/latest/doc/15-troubleshooting/)
+* [Upgrading](https://icinga.com/docs/icinga2/latest/doc/16-upgrading-icinga-2/)
 
-If you are a packager, please read the [development chapter](https://icinga.com/docs/icinga2/latest/doc/21-development/)
-for more details.
+Once Icinga Server and Web are running in your distributed environment,
+make sure to check out the many [Icinga modules](https://icinga.com/docs/)
+for even better monitoring.
 
 ## Documentation
 
@@ -74,6 +82,9 @@ contribution is appreciated!
 
 Please continue reading in the [contributing chapter](CONTRIBUTING.md).
 
+If you are a packager, please read the [development chapter](https://icinga.com/docs/icinga2/latest/doc/21-development/)
+for more details.
+
 ### Security Issues
 
 For reporting security issues please visit [this page](https://icinga.com/contact/security/).