docs: Update travis setup instructions

Closes dart-archive#1226

Author: vicb

bugs.txt

@@ -1,6 +1,6 @@
-= Travis-CI Setup Instructions
+# Travis-CI Setup Instructions
 
-== Set Up Instructions
+## Set Up Instructions
 
 1. Go to https://travis-ci.org/ and 'Sign in with Github'
 2. Visit https://travis-ci.org/profile to trigger a Github sync (this may take a minute)
@@ -9,26 +9,23 @@
 5. Scroll down to Travis and click it
 6. Click the 'Test Hook' button.
 
-== What does it do?
+## What does it do?
 
 - Every time you push to your repo, Travis will grab the changes from your repo and run a
   build on it.
-- The build runs on Chrome and Dartium stable browsers.
+- The build runs on Chrome, Firefox and Dartium browsers.
 
+## How does it work.
 
-== How does it work.
+All scripts can be found in `.travis.yml` and `scripts/travis` folder.
 
-All scripts can be found it `.travis.yml` and `./scripts/travis` folder.
-
-1. Install latest google-chrome
-2. Install Dart stable or dev channel (currently only running on stable, see `.travis.yml` `matrix`)
+1. Install the browsers (Chrome, Firefox and Dartium) 
+2. Install Dart stable or dev channel (see `CHANNEL` in the `.travis.yml` matrix)
 3. Run analyzer on the code
-4. Run karma on both Dartium (dart) and Chrome (dart2js)
+4. Run karma
 5. Generate documentation
+6. Merge "presubmit" branches into master when the build is successful
 
+## What needs to be done
 
-== What needs to be done
-
-- Publish generated documentation to a URL
-- If the branch is `presubmit`, then `github push upstream presubmit:master`
 - Collect/publish the test runs/times to some dashboard/graphing service