[master] ca0b9cf Update the -sfile documentation

[Martin Blix Grydeland]

commit ca0b9cfda2a9725bd045ac8c605925ed0d936ac9
Author: Martin Blix Grydeland <martin at varnish-software.com>
Date:   Tue Oct 7 16:25:00 2014 +0200

    Update the -sfile documentation

diff --git a/doc/sphinx/reference/varnishd.rst b/doc/sphinx/reference/varnishd.rst
index 4bc9cc9..8372086 100644
--- a/doc/sphinx/reference/varnishd.rst
+++ b/doc/sphinx/reference/varnishd.rst
@@ -179,7 +179,19 @@ file
 
 syntax: file,path[,size[,granularity]]
 
-The file backend stores data in a file on disk. The file will be accessed using mmap.
+The file backend stores data in a file on disk. The file will be
+accessed using mmap.
+
+The path is mandatory. If path points to a directory, a temporary file
+will be created in that directory and immediately unlinked. If path
+points to a non-existing file, the file will be created.
+
+If size is omitted, and path points to an existing file with a size
+greater than zero, the size of that file will be used. If not, an
+error is reported.
+
+Granularity sets the allocation block size. Defaults to the system
+page size or the filesystem block size, whichever is larger.
 
 persistent (experimental)
 ~~~~~~~~~~~~~~~~~~~~~~~~~