Remove BUCK file and update build documentation

The plugin is now built with Bazel. Remove the BUCK file and update the
documentation to describe how to build with Bazel.

Change-Id: I40a7b77b58ffdc20fec86e42eecafbbe3470cd9e

BUCK

diff --git a/BUCK b/BUCK
deleted file mode 100644
index f963c34..0000000
--- a/BUCK
+++ /dev/null
@@ -1,23 +0,0 @@
-include_defs('//lib/maven.defs')
-
-gerrit_plugin(
-  name = 'groovy-provider',
-  srcs = glob(['src/main/java/**/*.java']),
-  resources = glob(['src/main/**/*']),
-  manifest_entries = [
-    'Implementation-Title: Groovy Provider',
-    'Implementation-URL: https://gerrit.googlesource.com/plugins/scripting/groovy-provider',
-    'Gerrit-PluginName: groovy-provider',
-    'Gerrit-Module: com.googlesource.gerrit.plugins.scripting.groovyprovider.Module'
-  ],
-  deps = [
-    ':groovy',
-  ],
-)
-
-maven_jar(
-  name = 'groovy',
-  id = 'org.codehaus.groovy:groovy-all:2.2.1',
-  sha1 = '07ae565d50d24167c4e5d74b96f4126d4c56f16f',
-  license = 'Apache2.0',
-)

README.md

diff --git a/README.md b/README.md
index 5bc6f8d..a1e3258 100644
--- a/README.md
+++ b/README.md
@@ -3,16 +3,18 @@
 
 This plugin provides Groovy runtime environment for Gerrit plugins in Groovy.
 
-To build link this directory under Gerrit's tree plugins directory and run:
+To build, link this directory under Gerrit's tree plugins directory, merge
+the dependencies from external_plugin_deps.bzl into the file of the same
+name in the plugins directory, and from the root of the gerrit tree run:
 
 ```
-  buck build plugins/groovy-provider
+  bazel build plugins/groovy-provider
 ```
 
 The resulting artifact can be found under:
 
 ```
- buck-out/gen/plugins/groovy-provider/groovy-provider.jar
+ bazel-genfiles/plugins/groovy-provider/groovy-provider.jar
 ```
 
 To test deploy the review plugin [1] and copy this Groovy Provider plugin