Remove gwt-codeserver dependency mentions from site

gwt-codeserver is actually merged into gwt-dev since GWT 2.7, and while the
plugin supports GWT 2.6, it's probably not worth mentionning it.

Author: tbroyer

src/site/markdown/migrating.md.vm

@@ -6,7 +6,7 @@ The ${project.name} is very different from Mojo's Maven Plugin for GWT.
 
 To begin with, Mojo's plugin is tightly linked to a specific version of GWT,
 whereas the ${project.name} is [independent of the GWT version](usage.html).
-This means that when migrating, you have to add dependencies to `gwt-dev` and `gwt-codeserver` to your project.
+This means that when migrating, you have to add dependencies to `gwt-dev` to your project.
 
 The module is managed in `src/main/module.gwt.xml` by default.
 When migrating your project, you have to either move your module file to `src/main/module.gwt.xml`

src/site/markdown/usage.md.vm

@@ -42,10 +42,6 @@ $h2 Basic usage
           <groupId>com.google.gwt</groupId>
           <artifactId>gwt-dev</artifactId>
         </dependency>
-        <dependency>
-          <groupId>com.google.gwt</groupId>
-          <artifactId>gwt-codeserver</artifactId>
-        </dependency>
       </dependencies>
     </build>
     ```