Merge pull request #541 from w3c/onix-navigation-refactor

Updating Navigation in ONIX to reflect guidelines

a11y-meta-display-guide/2.0/draft/techniques/onix-metadata/index.html

@@ -658,7 +658,6 @@ <h4>Instructions</h4>
 					</li>
 					<li>
 						<span><b>IF</b> <var>table_of_contents_navigation</var> <b>OR</b> <var>index_navigation</var> <b>OR</b> <var>print_equivalent_page_numbering</var> <b>OR</b> <var>next_previous_structural_navigation</var>:</span>
-						<span><b>THEN</b> display <code id="navigation-intro">"Navigation by:"</code>.</span>
 						<ol class="condition">
 							<li>
 								<span><b>IF</b> <var>table_of_contents_navigation</var>:</span>
@@ -679,7 +678,7 @@ <h4>Instructions</h4>
 						</ol>
 					</li>
 					<li>
-						<b>ELSE</b> display <code id="navigation-no-metadata">"No information about navigation is available."</code>.
+						<b>ELSE</b> display <code id="navigation-no-metadata">"No information is available"</code>.
 						<p class="note">This key information can be hidden if metadata is missing.</p>
 					</li>
 				</ol>