doc: mention persistence caveats in sync man page

* man/sync.x ([BUGS]): Mention the caveats and reference
the system call man pages for more details.
Fixes http://bugs.gnu.org/19995

Debian bug #507085 reported by jidanni@jidanni.org

diff --git a/man/sync.x b/man/sync.x
index 79fee22700302d74c96119fef22a68e70b3f0a61..18ee3fc44ce03973c150245e678fa3a3a9dcbdb5 100644 (file)
--- a/man/sync.x
+++ b/man/sync.x
@@ -2,5 +2,8 @@
 sync \- Synchronize cached writes to persistent storage
 [DESCRIPTION]
 .\" Add any additional description here
+[BUGS]
+Persistence guarantees vary per system.
+See the system calls below for more details.
 [SEE ALSO]
 fdatasync(2), fsync(2), sync(2), syncfs(2)