[master] 606977bbf doc: Fix the cookie.keep_re() example

[Dridi Boukelmoune]

commit 606977bbfb624ead38e9c8648beac0b3906a4294
Author: Dridi Boukelmoune <dridi.boukelmoune at gmail.com>
Date:   Tue Apr 6 19:23:28 2021 +0200

    doc: Fix the cookie.keep_re() example
    
    Reported by Justin Lloyd.

diff --git a/vmod/vmod_cookie.vcc b/vmod/vmod_cookie.vcc
index ca13d0c0e..85e6b8519 100644
--- a/vmod/vmod_cookie.vcc
+++ b/vmod/vmod_cookie.vcc
@@ -124,7 +124,7 @@ Example::
 
 	sub vcl_recv {
 	    cookie.parse("cookie1: value1; cookie2: value2; cookie3: value3");
-	    cookie.keep_re("^cookie1,cookie2");
+	    cookie.keep_re("^cookie[12]$");
 	    # get_string() will now yield
 	    # "cookie1: value1; cookie2: value2;";
 	}