Improves a comment for gem install.
Improves a comment for gem install.

[#93835728](https://www.pivotaltracker.com/story/show/93835728)

Signed-off-by: Corey Innis <c6de6a297c7ba72017894924528d266f693d3f31@pivotal.io>

wcamarao/bosh-vsphere-cpi-release,cloudfoundry-incubator/bosh-vsphere-cpi-release,cloudfoundry-incubator/bosh-vsphere-cpi-release,nimbus-cloud/bosh-vsphere-cpi-release,rexxar-liang/bosh-vsphere-cpi-release,rexxar-liang/bosh-vsphere-cpi-release,cloudfoundry-incubator/bosh-vsphere-cpi-release,rexxar-liang/bosh-vsphere-cpi-release,wcamarao/bosh-vsphere-cpi-release,cloudfoundry-incubator/bosh-vsphere-cpi-release,nimbus-cloud/bosh-vsphere-cpi-release,cloudfoundry-incubator/bosh-vsphere-cpi-release,nimbus-cloud/bosh-vsphere-cpi-release,wcamarao/bosh-vsphere-cpi-release