Correct typo create_vocabulary.py doc-string (#71)

Author: blackhat-coder

examples/bert/create_vocabulary.py

@@ -11,7 +11,7 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-"""Create BERT workpiece vocabularies.
+"""Create BERT wordpiece vocabularies.
 
 This script will create wordpiece vocabularies suitable for pretraining BERT.