Corrected info on how to install Darcula plugin

[jkovalsky]

Since the legacy Plugin Portal hosted on Oracle infrastructure is no longer available I am proposing to direct users to the archived version of NetBeans 8.2 standard distribution plugin catalog where the Darcula plugin is still accessible.

[advra]

Great addition to the information. I was having trouble modifying the pom. Almost more trouble than its worth. Adding the old 8.2 distribution catalog and installing right from the menu worked perfectly.

[advra]

The repos have been unreliable lately. Consider uploading the pre-compiled jar as a release in github http://plugins.archive.librebeans.org/nbms/1501524971_nb-darcula-1.6.nbm

[jkovalsky]

Ideally please consider uploading the plugin to Maven Central repository and registering in NetBeans Plugin Portal directly. For more information see here.

[advra]

I agree but thats up to Revivus as he is original author