Merge branch 'elasticsearch-pathfix-docs' into 'master'

Fix ES indexer install script - remove leading /

See merge request gitlab-org/gitlab-ce!28231

doc/integration/elasticsearch.md

@@ -85,7 +85,7 @@ To build and install the indexer, run:
 
 ```sh
 git clone https://gitlab.com/gitlab-org/gitlab-elasticsearch-indexer.git
-cd /gitlab-elasticsearch-indexer
+cd gitlab-elasticsearch-indexer
 make
 sudo make install
 ```