update travis

.travis.yml

@@ -61,4 +61,16 @@ script:
   - cmake ..
   - cmake --build . --config Release -- -j4
   - ctest -C Release -V
-  - cd ..
+
+deploy:
+  provider: pages
+  skip_cleanup: true
+  local_dir: docs/html
+  github_token: $GH_REPO_TOKEN
+  on:
+    branch: master
+  scripts: doxygen Doxyfile
+  addons:
+    apt:
+      packages:
+        - doxygen