Added 3.29.0 to docs.yaml

Author: Bret McGuire

docs.yaml

@@ -22,6 +22,8 @@ sections:
       # build extensions like libev
       CASS_DRIVER_NO_CYTHON=1 python setup.py build_ext --inplace --force
 versions:
+  - name: '3.29'
+    ref: 1a947f84
   - name: '3.28'
     ref: 4325afb6
   - name: '3.27'