Merge pull request #3311 from travis-ci/qasim-at-tci-docker-compose

Update docker.md

Author: nrios14

user/docker.md

@@ -181,7 +181,7 @@ by adding the following `before_install` step to your `.travis.yml`:
 
 ```yaml
 env:
-  - DOCKER_COMPOSE_VERSION=1.4.2
+  - DOCKER_COMPOSE_VERSION=v2.17.3
 
 before_install:
   - sudo rm /usr/local/bin/docker-compose