elements -> component elements

@afs' suggestion #12
https://gist.github.com/afs/f71020019fc33b4ded3e105339c6a655

Author: pchampin

spec/index.html

@@ -923,7 +923,7 @@ <h3>Literals</h3>
     <p>Literals are used for values such as strings, numbers, and dates.</p>
 
     <p>A <dfn data-local-lt="RDF literal">literal</dfn> in an <a>RDF graph</a> consists of
-      two, three, or four elements, as follows:</p>
+      two, three, or four component elements, as follows:</p>
 
     <ol>
       <li>A <dfn>lexical form</dfn>, being an <a data-lt="string">RDF string</a>.