SELinux validate:  Improve documentation.

When grep'ing for denials, look for avc:, not AVC.
Explain usage of newer audit2allow versions.

Change-Id: Idd6d9b448314fc147e0d3c89aed9d3025fced99f
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
1 file changed