DOC: travis file with python 3.6

Author: licode

.travis.yml

@@ -2,15 +2,18 @@ language : python
 sudo: false
 env:
   global:
-    python: "3.5"
-    BUILD_DOCS: true
     BUILD_DOCS_BRANCH: master
     DOCS_SUBDIR: .
     TARGET_DEV_SUBDIR: .
     HTML_SUBDIR: build/html
     DOCS_CONDA_DEPS: 'bluesky'
     DOCS_PIP_DEPS: ''
 
+matrix:
+  include:
+    - python: 3.6
+      env: BUILD_DOCS=true
+
 before_install:
   - git clone https://github.com/NSLS-II/nsls2-ci --branch master --single-branch ~/ci_scripts
   - source ~/ci_scripts/install-miniconda.sh