Reference SAI Authorization Agent + link SAI in §4 discovery note

- §2.1 access-control bullet: name the SAI Authorization Agent as a
  concrete example of an access-management Client (per @elf-pavlik on
  PR #776).
- §4 data discovery note: hyperlink Solid Application Interoperability
  to TR/sai. Add an editor's note that a Type Indexes link will be
  added once PR #786 (which lists Type Indexes as a TR work item) is
  merged.

Author: jeswr

solid26.html

@@ -413,7 +413,7 @@ <h4><span>Note</span></h4>
                       <ul>
                         <li>access requests to update access control rules accordingly on a Server</li>
                         <li>issued by the application-logic Client</li>
-                        <li>processed by a particular Client that is able and trusted to manage access controls (such as an access management or authorization application)</li>
+                        <li>processed by a particular Client that is able and trusted to manage access controls (such as an access management or authorization application; e.g. the <a href="https://solid.github.io/data-interoperability-panel/specification/#authorization-redirect-endpoint">Authorization Agent</a> defined by <a href="https://solidproject.org/TR/sai">Solid Application Interoperability</a>)</li>
                       </ul>
                       </li>
                     </ul>
@@ -632,7 +632,8 @@ <h4><span>Note</span></h4>
 
               <div class="note">
                 <h4><span>Note</span></h4>
-                <p>Data discovery beyond the profile varies across the ecosystem. Within the <a href="https://solidproject.org/TR/">Solid TR work items</a> the relevant mechanisms are Type Indexes and Solid Application Interoperability (SAI); many additional bespoke mechanisms are in active use outside the TR work items. This guide does not prescribe a single mechanism.</p>
+                <p>Data discovery beyond the profile varies across the ecosystem. Within the <a href="https://solidproject.org/TR/">Solid TR work items</a> the relevant mechanisms are Type Indexes and <a href="https://solidproject.org/TR/sai">Solid Application Interoperability (SAI)</a>; many additional bespoke mechanisms are in active use outside the TR work items. This guide does not prescribe a single mechanism.</p>
+                <p><em>Editor's note: a link to the Type Indexes specification will be added once <a href="https://github.com/solid/specification/pull/786">PR #786</a> is merged.</em></p>
               </div>
 
             </div>