Merge pull request #250 from w3c/pri-hazard

Updated hazard and fixed typo

UX-Guide-Metadata/draft/principles/index.html

@@ -293,7 +293,7 @@ <h4>Examples</h4>
 							<!--if Display transformability is present-->
 							<li>Appearance cannot be modified.</li>
 							<!--if display transformability is not present and text on visual is present-->
-							<li>Appearance Modifiability not known.</li>
+							<li>Ability to modify the appearance is not known.</li>
 							<!--if neither display transformability nor text on visual are presents-->
 						</ul>
 					</aside>
@@ -714,7 +714,8 @@ <h3>Hazards</h3>
 					negatively. This is because users search for content that is safe for them as well as want to know
 					when content is potentially dangerous to them.</p>
 
-				<p>This group should always be displayed. Indicate that no metadata is provided if that is the case.</p>
+				<p>The hazards property vocabulary includes a value of unknown, which means the content creator of the metadata explicitly acknowledges that the resource has not been checked for hazards. This is different than providing no metadata for this property which does not carry any meaning.
+</p>
 
 				<section id="hazards-examples">
 					<h4>Examples</h4>