[6.0] ab15cd458 sync std.fileread() docs with reality

[Dridi Boukelmoune]

commit ab15cd458734dd64c616c158100da1c04439b251
Author: Nils Goroll <nils.goroll at uplex.de>
Date:   Mon May 14 09:18:42 2018 +0200

    sync std.fileread() docs with reality
    
    The blind caching is OBE for six years now, see
    344a709ccf9559f3d8e5d7a0a9a35c6e94705f0f

diff --git a/lib/libvmod_std/vmod.vcc b/lib/libvmod_std/vmod.vcc
index 34b6399aa..c8305ae9d 100644
--- a/lib/libvmod_std/vmod.vcc
+++ b/lib/libvmod_std/vmod.vcc
@@ -107,10 +107,8 @@ Example
 $Function STRING fileread(PRIV_CALL, STRING)
 
 Description
-	Reads a file and returns a string with the content. Please
-	note that it is not recommended to send variables to this
-	function the caching in the function doesn't take this into
-	account. Also, files are not re-read.
+	Reads a file and returns a string with the content. The result
+	is cached indefinitely per filename.
 Example
 	synthetic("Response was served by " + std.fileread("/etc/hostname"));