[master] 18d8ab242 clarify previous commit

[Nils Goroll]

commit 18d8ab242cf6cddc42ed49f1fdf74d525a423740
Author: Nils Goroll <nils.goroll at uplex.de>
Date:   Thu Oct 25 16:17:26 2018 +0200

    clarify previous commit
    
    ... after feedback from @slimhazard aka Geoff

diff --git a/doc/sphinx/reference/vmod.rst b/doc/sphinx/reference/vmod.rst
index 46ad29d5d..d8cf6e4b0 100644
--- a/doc/sphinx/reference/vmod.rst
+++ b/doc/sphinx/reference/vmod.rst
@@ -268,8 +268,8 @@ language representation.  Here is a description of them.
 All but the PRIV and STRING_LIST types have typedefs: VCL_INT, VCL_REAL,
 etc.
 
-Notice that all the non-native (C pointer) types are ``const``, so
-anything returned by a vmod function/method is assumed to be
+Notice that most of the non-native (C pointer) types are ``const``,
+which, if returned by a vmod function/method, are assumed to be
 immutable. In other words, a vmod `must not` modify any data which was
 previously returned.
 
@@ -339,7 +339,7 @@ HEADER
 HTTP
 	C-type: ``struct http *``
 
-	TODO
+	A reference to a header object as ``req.http`` or ``bereq.http``.
 
 INT
 	C-type: ``long``