escape \0

doc/sphinx/reference/vcl.rst

@@ -420,7 +420,7 @@ hash_data(str)
 
 regsub(str, regex, sub)
   Returns a copy of str with the first occurrence of the regular 
-  expression regex replaced with sub. Within sub, \0 (which can 
+  expression regex replaced with sub. Within sub, \\0 (which can 
   also be spelled &) is replaced with the entire matched string, 
   and \n is replaced with the contents of subgroup n in the 
   matched string.