Apply suggestion from @simonstey

Author: simonstey

shacl12-rules/index.html

@@ -342,7 +342,7 @@ <h2>Shape Rules Abstract Syntax</h2>
           <dt><dfn>triple template</dfn></dt>
           <dd>
             A [=triple template=] is 3-tuple where each element is either
-            a [=variable=] or an [=RDF term] (which might be a [=triple term=]).
+            a [=variable=] or an [=RDF term=] (which might be a [=triple term=]).
             The second element of the tuple must be an [=IRI=] or a [=variable=].
             [=Triple templates=] appear in the [=head=] of a [=rule=].
           </dd>