s/_/./ in reference name.  man-refs.ent uses conservative naming charset
of LCNMCHAR, UCNMCHAR, LCNMSTRT, and UCNMSTRT.


git-svn-id: svn+ssh://svn.freebsd.org/doc/head@45729 c2e8774f-c49f-e111-b436-862b2bbc8956