Update oo_deployment_guide_comprehensive.adoc

yum install -y mongodb-server didn't actually install the mongodb package as a dependency, and I had to install it separately. Therefore I have added mongodb to the yum install line to save time/troubleshooting for others.
<docs> Added libmongodb to the yum install command for MongoDB
Merge pull request #3953 from keirwhitlock/docupdates

Merged by openshift-bot