Role Row: Editorial revisions to changes in PR #789

For issue #558, Make changes in response to feedback from @jnurthen and @carmacleod:
* Change author SHOULD NOT to MUST NOT use setsize, posinset, level, and expanded attributes in treegrids
* change treegrids to tree grids in one place where not referring specifically to the treegrid role.

index.html

@@ -5601,8 +5601,8 @@ <h5>Presentational Roles Conflict Resolution</h5>
 				<p>A row of cells in a tabular container.</p>
 				<p>Rows contain <rref>cell</rref> or <rref>gridcell</rref> <a>elements</a>, and thus serve to organize a <rref>table</rref>, <rref>grid</rref>, or <rref>treegrid</rref>.</p>
 			  <p>
-          While the row role can be used in <rref>tables</rref>, <rref>grids</rref>, and <rref>treegrids</rref>, the semantics of <sref>aria-expanded</sref>, <pref>aria-posinset</pref>, <pref>aria-setsize</pref>, and <pref>aria-level</pref> are only applicable to the hierarchical structure of an interactive treegrid.
-          Therefore, authors SHOULD NOT apply <sref>aria-expanded</sref>, <pref>aria-posinset</pref>, <pref>aria-setsize</pref>, and <pref>aria-level</pref> to a <rref>row</rref> that descends from a <rref>table</rref> or <rref>grid</rref>, and user agents SHOULD NOT expose any of these four properties to assistive technologies unless the <rref>row</rref> descends from a <rref>treegrid</rref>.
+          While the row role can be used in <rref>tables</rref>, <rref>grids</rref>, and <rref>treegrids</rref>, the semantics of <sref>aria-expanded</sref>, <pref>aria-posinset</pref>, <pref>aria-setsize</pref>, and <pref>aria-level</pref> are only applicable to the hierarchical structure of an interactive tree grid.
+          Therefore, authors MUST NOT apply <sref>aria-expanded</sref>, <pref>aria-posinset</pref>, <pref>aria-setsize</pref>, and <pref>aria-level</pref> to a <rref>row</rref> that descends from a <rref>table</rref> or <rref>grid</rref>, and user agents SHOULD NOT expose any of these four properties to assistive technologies unless the <rref>row</rref> descends from a <rref>treegrid</rref>.
         </p>
 				<p>Authors MUST ensure <a>elements</a> with <a>role</a> <code>row</code> are contained in, or <a>owned</a> by, an element with the role <rref>table</rref>, <rref>grid</rref>, <rref>rowgroup</rref>, or <rref>treegrid</rref>.</p>
 			</div>