Update docs: TravisCI now supports rvm: - truffleruby

Author: eregon

doc/user/standalone-distribution.md

@@ -16,11 +16,23 @@ truffleruby-VERSION-linux-amd64.tar.gz
 truffleruby-VERSION-macos-amd64.tar.gz
 ```
 
+## Testing TruffleRuby in TravisCI
+
+TruffleRuby is now integrated in TravisCI.
+Just add `truffleruby` in the build matrix, such as:
+
+```yaml
+language: ruby
+rvm:
+  - 2.6.0
+  - truffleruby
+```
+
+See https://docs.travis-ci.com/user/languages/ruby#truffleruby for details.
+Please [report](https://github.com/oracle/truffleruby/issues) any issue you might find while testing with TruffleRuby.
+
 ## Testing TruffleRuby in CI
 
-The standalone distributions are also useful for testing, for instance to test
-TruffleRuby in your continuous integration system. If you use TravisCI,
-[see below](#testing-truffleruby-in-travisci).
 If you use another continuous integration system, you can follow these
 instructions to run TruffleRuby in CI.
 
@@ -45,34 +57,6 @@ TruffleRuby uses the correct `GEM_HOME` and `GEM_PATH`. This is the reason for
 See [Using TruffleRuby without a Ruby manager](ruby-managers.md#using-truffleruby-without-a-ruby-manager)
 for details.
 
-## Testing TruffleRuby in TravisCI
-
-For TravisCI, we
-[plan to integrate](https://github.com/travis-ci/travis-ci/issues/9803)
-directly so one could just use `rvm: truffleruby` in the build matrix.
-However, this is not complete yet. In the meantime, the following example
-configuration can be used.
-
-Set `TRUFFLERUBY_VERSION` to the latest TruffleRuby version from
-[GitHub releases](https://github.com/oracle/truffleruby/releases).
-
-```yaml
-script:
-  - bundle exec rspec
-matrix:
-  include:
-  - rvm: 2.5.1
-  - name: TruffleRuby
-    rvm: system
-    install:
-      - export TRUFFLERUBY_VERSION=<desired_version>
-      - curl -L https://github.com/oracle/truffleruby/releases/download/vm-$TRUFFLERUBY_VERSION/truffleruby-$TRUFFLERUBY_VERSION-linux-amd64.tar.gz | tar xz
-      - export PATH="$PWD/truffleruby-$TRUFFLERUBY_VERSION-linux-amd64/bin:$PATH"
-      - $PWD/truffleruby-$TRUFFLERUBY_VERSION-linux-amd64/lib/truffle/post_install_hook.sh
-      - gem install bundler
-      - bundle install
-```
-
 ## Dependencies
 
 [TruffleRuby's dependencies](../../README.md#dependencies) need to be installed