try to explain beresp gzip stuff

doc/sphinx/reference/vcl.rst

@@ -470,9 +470,6 @@ vcl_fetch
   error code [reason]
     Return the specified error code to the client and abandon the request.
 
-  esi
-     ESI-process the document which has just been fetched.
-
   pass
     Switch to pass mode.  Control will eventually pass to vcl_pass.
 
@@ -646,6 +643,22 @@ The following variables are available after the requested object has
 been retrieved from the backend, before it is entered into the cache. In
 other words, they are available in vcl_fetch:
 
+beresp.do_esi
+  ESI-process the object after fetching it. Defaults to 0. Set it to 1 to 
+  activate ESI.
+
+beresp.do_gzip
+  Gzip the object before storing it. Defaults to 1, 
+
+beresp.is_gzip
+  True if the object is compressed.
+
+beresp.do_gunzip
+  Unzip the object before storing it. 
+
+beresp.is_gunzip 
+  True if the object is not compressed.
+
 beresp.proto
   The HTTP protocol version used when the object was retrieved.