Merge pull request #651 from travis-ci/sw-event-type

Added TRAVIS_EVENT_TYPE

Author: plaindocs

user/environment-variables.md

@@ -179,6 +179,7 @@ to tag the build, or to run post-build deployments.
 * `TRAVIS_COMMIT`: The commit that the current build is testing.
 * `TRAVIS_COMMIT_RANGE`: The range of commits that were included in the push
   or pull request.
+* `TRAVIS_EVENT_TYPE`: Indicates how the build was triggered. One of `push`, `pull_request`, `api`, `cron`.
 * `TRAVIS_JOB_ID`: The id of the current job that Travis CI uses internally.
 * `TRAVIS_JOB_NUMBER`: The number of the current job (for example, "4.1").
 * `TRAVIS_OS_NAME`: On multi-OS builds, this value indicates the platform the job is running on.