added travis doc

.travis.yml

@@ -1,8 +1,11 @@
+# As there is (still) no Travis Lua language support, we use the fine
+# https://github.com/mpeterv/hererocks local environment build to set
+# up a local Lua/luarocks/packages environment.
 language: python
 sudo: false
 
 before_install:
-  - ./env.sh
+  - ./env.sh # installs the local environment.
 
 script:
-  - ./env.sh busted
+  - ./env.sh busted # runs all tests.