Promote configuration of apidocRootPackage (#129)

... to be a mandatory step.

Author: Synesso

README.md

@@ -9,10 +9,23 @@ A [paradox](https://github.com/lightbend/paradox/) directive that automatically
 
 ## Usage
 
+Add the plugin:
+
 ```scala
 addSbtPlugin("com.lightbend.paradox" % "sbt-paradox-apidoc" % "<latest>")
 ```
 
+Configure the `apidocRootPackage` within your paradox settings:
+
+```
+import com.lightbend.paradox.apidoc.ApidocPlugin.autoImport.apidocRootPackage
+
+(...)
+  apidocRootPackage := "akka",
+(...)
+```
+
+
 You can now create 'grouped' javadoc/scaladoc references in paradox like:
 
 ```
@@ -79,17 +92,6 @@ produce an unambigious result, you will have to use the FQCN.
     * Java: method - `akka/stream/javadsl/Flow.html#method()`
 
 
-To limit the packages that are searched for classes, configure the
-`apidocRootPackage` setting:
-
-```
-import com.lightbend.paradox.apidoc.ApidocPlugin.autoImport.apidocRootPackage
-
-(...)
-  apidocRootPackage := "akka",
-(...)
-```
-
 ### When only Scaladoc is generated
 
 If the project does not publish Javadoc, the corresponding Javadoc base URL can be cleared and the Java links will point to the `javadsl` package in the Scaladocs.