DOC: typo: req.uri is now replaced by capture.req.uri

A configuration example was not updated after the switch from req.uri to
capture.req.uri.

backport: 1.5 and above

doc/configuration.txt

@@ -6654,8 +6654,8 @@ redirect scheme   <sch> [code <code>] <option> [{if | unless} <condition>]
         redirect scheme https if !{ ssl_fc }
 
   Example: append 'www.' prefix in front of all hosts not having it
-        http-request redirect code 301 location www.%[hdr(host)]%[req.uri] \
-          unless { hdr_beg(host) -i www }
+        http-request redirect code 301 location \
+          www.%[hdr(host)]%[capture.req.uri] unless { hdr_beg(host) -i www }
 
   See section 7 about ACL usage.