Fix delimeter typo

Author: Jan-Olof Hendig

doc/Language/grammars.pod6

@@ -137,7 +137,7 @@ name of the alternation is attached with C<< :sym<> >> adverb.
 In the actions class, we now got rid of the ternary operator and simply take
 the C<.made> value from the C<< $<calc-op> >> match object. And the actions for
 individual alternations now follow the same naming pattern as in the grammar:
-C<< method calc-op:sym<add> >> and C<method calc-op:sym<sub> >>.
+C<< method calc-op:sym<add> >> and C<<method calc-op:sym<sub> >>.
 
 The real beauty of this method can be seen when you subclass that grammar
 and actions class. Let's say we want to add a multiplication feature to the