Correct erroneous info on default <ws> token

doc/Language/grammars.pod6

@@ -192,10 +192,21 @@ Is the same as:
 
     token entry { <key> <.ws> ’=’ <.ws> <value> <.ws> } # . = non-capturing
 
-The default C<ws> matches "whitespace", such a sequence of spaces (of whatever
-type), newlines, unspaces, or heredocs.
-
-It's perfectly fine to provide your own C<ws> token:
+The default C<ws> matches one or more whitespace characters (C<\s>) or a
+word boundary (C«<|w>»):
+
+    # First <.ws> matches word boundary at the start of the line
+    # and second <.ws> matches the whitespace between 'b' and 'c'
+    say 'ab   c' ~~ /<.ws> ab <.ws> c / # OUTPUT: «｢ab   c｣␤»
+    
+    # Failed match: there neither any whitespace nor a word
+    # boundary between 'a' and 'b'
+    say 'ab' ~~ /. <.ws> b/ # OUTPUT: «Nil␤»
+    
+    # Successful match: there is a word boundary between ')' and 'b'
+    say ')b' ~~ /. <.ws> b/ # OUTPUT: «｢)b｣␤»
+
+You can also redefine the default C<ws> token:
 
     grammar Foo {
         rule TOP { \d \d }