Non-Modal Dialog Pattern: Remove stub section and links to it

In aria-practices.html,
as part of preparation for release publication,
since the non-modal dialog pattern section had no content,
removed the section and two links that referenced it.

aria-practices.html

@@ -930,7 +930,7 @@ <h3>Dialog (Modal)</h3>
         and in some implementations, attempts to interact with the inert content cause the dialog to close.
       </p>
       <p>
-        Like <a href="#dialog_nonmodal">non-modal dialogs</a>, modal dialogs contain their tab sequence.
+        Like non-modal dialogs, modal dialogs contain their tab sequence.
         That is, <kbd>Tab</kbd> and <kbd>Shift + Tab</kbd> do not move focus outside the dialog.
         However, unlike most non-modal dialogs, modal dialogs do not provide means for moving keyboard focus outside the dialog window without closing the dialog.
       </p>
@@ -1049,11 +1049,6 @@ <h4>WAI-ARIA Roles, States, and Properties</h4>
       </section>
     </section>
 
-    <section class="widget" id="dialog_nonmodal">
-      <h3>Dialog (Non-Modal)</h3>
-      <p>Drafting content for this section is tracked by <a href="https://github.com/w3c/aria-practices/issues/59">issue 59</a>. </p>
-    </section>
-
     <section class="widget" id="disclosure">
       <h3>Disclosure (Show/Hide)</h3>
       <p>
@@ -2515,8 +2510,7 @@ <h3>Tooltip Widget</h3>
       </p>
       <p>
         Tooltip widgets do not receive focus.
-        A hover that contains focusable elements can be made using the
-        a <a href="#dialog_nonmodal">non-modal dialog pattern</a>.
+        A hover that contains focusable elements can be made using a non-modal dialog.
       </p>
       <section class="notoc">
         <h4>Example</h4>