ssl: Update documentation

lib/ssl/doc/src/ssl.xml

@@ -1307,9 +1307,15 @@ fun(srp, Username :: binary(), UserState :: term()) ->
 	extension in its certificate request message that will be sent if the
 	option <c>verify</c> is set to <c>verify_peer</c>. Defaults to <c>true</c>.</p>
 
-	<p>A reason to exclude the extension would be if the server wants to communicate with clients
+	<p>If set to <c>false</c> for older TLS versions its corresponding certificate authorities
+	definition in its certificate request will be set to the empty list instead of
+	including the appropriate certificate authorities. This has the same affect
+	as excluding the TLS-1.3 extension.
+	</p>
+
+	<p>A reason to exclude the certificate authorities would be if the server wants to communicate with clients
 	incapable of sending complete certificate chains that adhere to the
-	extension, but the server still has the capability to recreate a chain that it can verify.</p>
+	certificate authorities, but the server still has the capability to recreate a chain that it can verify.</p>
 
       </desc>