[6.0] 39d6244ac Document do_g[un]zip wrt http_gzip_support

[Federico G. Schwindt]

commit 39d6244acfc19fdc646c0f9bbf3cefb6a3faecbe
Author: Federico G. Schwindt <fgsch at lodoss.net>
Date:   Tue Mar 27 09:02:12 2018 -0300

    Document do_g[un]zip wrt http_gzip_support
    
    Addresses #2626.

diff --git a/doc/sphinx/reference/vcl_var.rst b/doc/sphinx/reference/vcl_var.rst
index 253da0bea..c4ded7c3e 100644
--- a/doc/sphinx/reference/vcl_var.rst
+++ b/doc/sphinx/reference/vcl_var.rst
@@ -739,6 +739,9 @@ beresp.do_gzip
 
 	Set to `true` to gzip the object while storing it.
 
+	If `http_gzip_support` is disabled, setting this variable
+	has no effect.
+
 beresp.do_gunzip
 
 	Type: BOOL
@@ -752,6 +755,9 @@ beresp.do_gunzip
 	Set to `true` to gunzip the object while storing it in the
 	cache.
 
+	If `http_gzip_support` is disabled, setting this variable
+	has no effect.
+
 beresp.was_304
 
 	Type: BOOL