State some support exists

Author: afs

spec/index.html

@@ -1006,7 +1006,7 @@ <h3>Literals</h3>
     <section>
       <h4>Representation of Literals</h4>
 
-      <p>Some concrete syntaxes MAY support
+      <p>Some concrete syntaxes support
         <dfn data-lt="simple literal" class="export">simple literals</dfn> consisting of only a
         <a>lexical form</a> without any <a>datatype IRI</a>, <a>language tag</a>, or <a>base direction</a>.
         Simple literals are syntactic sugar for abstract syntax