Update _using-vol-services.html.md.erb
Update _using-vol-services.html.md.erb

- Include a description of Cloud Foundry file access behavior when UID is not specified in the NFS service.
- Document the limitation that hard links are not supported when UID mapping is enabled in NFS.
[#171841425](https://www.pivotaltracker.com/story/show/171841425)
cloudfoundry/docs-dev-guide