Add a bug admonition (https://squidfunk.github.io/mkdocs-material/extensions/admonition/#bug) with the title "EL7 version compatibility" to the top of the following documents:
https://opensciencegrid.org/docs/data/xrootd/install-standalone/
https://opensciencegrid.org/docs/data/xrootd/install-storage-element/
https://opensciencegrid.org/docs/data/xrootd/xrootd-authorization/
https://opensciencegrid.org/docs/data/xrootd/install-client/
The CVMFS incompatibility is due to an old version of selinux-policy while the XRootD incompatibility is due to issues with `xrootd-lcmaps`.
We can hold off on addressing this ticket until the doc focus on 2017-07-25