Change request name to active-generator-names

The previous name was cryptic and did not match to return value.

src/main/java/world/bentobox/magiccobblestonegenerator/request/ActiveGeneratorNamesRequestHandler.java

@@ -25,7 +25,7 @@ public class ActiveGeneratorNamesRequestHandler extends AddonRequestHandler
 {
     public ActiveGeneratorNamesRequestHandler(StoneGeneratorAddon addon)
     {
-        super("magic-generator-type");
+        super("active-generator-names");
         this.addon = addon;
     }