message: Add mandatory "gen_base_package" argument in the usage example
diff: @@ -8,11 +8,11 @@ load("//tensorflow:tensorflow.bzl", "tf_copts")
  # Then, combine all those source files into a single archive (.srcjar).
  #
  # For example:
  -# tf_java_op_gen_srcjar("gen_sources", "gen_tool", [ "array_ops", "math_ops" ])
  +# tf_java_op_gen_srcjar("gen_sources", "gen_tool", "my.package", [ "array_ops", "math_ops" ])
  #
  # will create a genrule named "gen_sources" that first generate source files:
  -# ops/src/main/java/org/tensorflow/op/array/*.java
  -# ops/src/main/java/org/tensorflow/op/math/*.java
  +# ops/src/main/java/my/package/array/*.java
  +# ops/src/main/java/my/package/math/*.java
  #
  # and then archive those source files in:
  # ops/gen_sources.srcjar
  