Discontinue publishing of Maven archetypes

This project is a non Maven project in second generation: Buck, Bazel.
We discourage usage of Maven and not maintaining the tool chain. To
start writing gerrit plugins there are enough resources:

* more than 100 production ready plugins
* cookbook-plugin
* examples plugins, pending for review: [1].

* https://gerrit-review.googlesource.com/91698

Change-Id: I322e9b77f7daa26ea9927231d57f292919974ffe

Documentation/dev-plugins.txt

@@ -25,29 +25,8 @@ Most of this documentation refers to either type as a plugin.
 [[getting-started]]
 == Getting started
 
-To get started with the development of a plugin there are two
-recommended ways:
-
-. use the Gerrit Plugin Maven archetype to create a new plugin project:
-+
-With the Gerrit Plugin Maven archetype you can create a skeleton for a
-plugin project.
-+
-----
-mvn archetype:generate -DarchetypeGroupId=com.google.gerrit \
-    -DarchetypeArtifactId=gerrit-plugin-archetype \
-    -DarchetypeVersion=2.14-SNAPSHOT \
-    -DgroupId=com.googlesource.gerrit.plugins.testplugin \
-    -DartifactId=testplugin
-----
-+
-Maven will ask for additional properties and then create the plugin in
-the current directory. To change the default property values answer 'n'
-when Maven asks to confirm the properties configuration. It will then
-ask again for all properties including those with predefined default
-values.
-
-. clone the sample plugin:
+To get started with the development of a plugin clone the sample
+plugin:
 +
 This is a project that demonstrates the various features of the
 plugin API. It can be taken as an example to develop an own plugin.
@@ -57,11 +36,8 @@ $ git clone https://gerrit.googlesource.com/plugins/cookbook-plugin
 ----
 +
 When starting from this example one should take care to adapt the
-`Gerrit-ApiVersion` in the `pom.xml` to the version of Gerrit for which
-the plugin is developed. If the plugin is developed for a released
-Gerrit version (no `SNAPSHOT` version) then the URL for the
-`gerrit-api-repository` in the `pom.xml` needs to be changed to
-`https://gerrit-api.storage.googleapis.com/release/`.
+`Gerrit-ApiVersion` in the `BUILD` to the version of Gerrit for which
+the plugin is developed.
 
 [[API]]
 == API
@@ -1695,26 +1671,6 @@ public class MyTopMenuExtension implements TopMenu {
 == GWT UI Extension
 Plugins can extend the Gerrit UI with own GWT code.
 
-The Maven archetype 'gerrit-plugin-gwt-archetype' can be used to
-generate a GWT plugin skeleton. How to use the Maven plugin archetypes
-is described in the link:#getting-started[Getting started] section.
-
-The generated GWT plugin has a link:#top-menu-extensions[top menu] that
-opens a GWT dialog box when the user clicks on it.
-
-In addition to the Gerrit-Plugin API a GWT plugin depends on
-`gerrit-plugin-gwtui`. This dependency must be specified in the
-`pom.xml`:
-
-[source,xml]
-----
-<dependency>
-  <groupId>com.google.gerrit</groupId>
-  <artifactId>gerrit-plugin-gwtui</artifactId>
-  <version>${Gerrit-ApiVersion}</version>
-</dependency>
-----
-
 A GWT plugin must contain a GWT module file, e.g. `HelloPlugin.gwt.xml`,
 that bundles together all the configuration settings of the GWT plugin: