 Merge branch 'improve_installation_guide' into 'master'
 Merge branch 'improve_installation_guide' into 'master'

Improve Installation Guide

Current readme is really confusing so improvements were necessary.

/cc @sytse @jacobvosmaer

Wolfium/gitlab-ci-runner-centos,myrubapa/gitlab-ci-runner-centos,gitlabhq/gitlab-ci-runner,andrewmunsell/gitlab-ci-runner,Wolfium/gitlab-ci-runner-centos,moos3/gitlab-ci-runner-centos,gitlabhq/gitlab-ci-runner,andrewmunsell/gitlab-ci-runner,mfittko/gitlab-ci-runner,myrubapa/gitlab-ci-runner-centos,cui-liqiang/gitlab-ci-runner,cui-liqiang/gitlab-ci-runner,moos3/gitlab-ci-runner-centos,mfittko/gitlab-ci-runner