Make the Example section more concise (Issue #42).

New update according to comments of PR #64.

Overview.src.html

@@ -566,16 +566,13 @@ <h3>
   var presUrl = "http://example.com/presentation.html";
   // create random presId 
   var presId = Math.random().toFixed(6).substr(2);
-  navigator.presentation.startSession(presUrl, presId).then(function(newSession){
-    // a new session is started successfully
-    setSession(newSession);
-  },function(){
+  // Start new session. presId is optional.
+  // the new started session will be passed to setSession on success or null on error
+  navigator.presentation.startSession(presUrl, presId).then(setSession).catch(function(e){
     // user cancels the selection dialog or an error is occurred
     setSession(null);
   });
 &lt;/script&gt;
-
-
 </pre>
       </section>
       <section>
@@ -587,17 +584,13 @@ <h3>
 &lt;script&gt;
   // read presId from localStorage if exists 
   var presId = localStorage &amp;&amp; localStorage["presId"] || null;
-  // presId is mandatory for joinSession
-  presId &amp;&amp; navigator.presentation.joinSession(presUrl, presId).then(function(existingSession){
-    // session with requested presUrl and presId is found and joined successfully
-    setSession(existingSession);
-  },function(){
-    // no session found for presUrl and presId or error is occurred 
+  // presId is mandatory for joinSession.
+  // The joined session will be passed to setSession on success or null on error
+  presId &amp;&amp; navigator.presentation.joinSession(presUrl, presId).then(setSession).catch(function(e){
+    // no session found for presUrl and presId or an error is occurred
     setSession(null);
   });
 &lt;/script&gt;
-
-
 </pre>
       </section>
       <section>
@@ -632,8 +625,6 @@ <h3>
     }
   };
 &lt;/script&gt;
-
-
 </pre>
         <pre class="example">
 &lt;!-- presentation.html --&gt;
@@ -648,8 +639,6 @@ <h3>
       session.postMessage("hello");
   };
 &lt;/script&gt;
-
-
 </pre>
       </section><!--
       <p>

index.html

@@ -78,8 +78,8 @@
       <h1>
         Presentation API
       </h1>
-      <h2 class="no-num no-toc" id="editor's-draft-16-march-2015">
-        Editor's Draft 16 March 2015
+      <h2 class="no-num no-toc" id="editor's-draft-18-march-2015">
+        Editor's Draft 18 March 2015
       </h2>
       <dl>
         <dt>
@@ -640,16 +640,13 @@ <h3 id="starting-a-new-presentation-session-example"><span class="secno">5.2 </s
   var presUrl = "http://example.com/presentation.html";
   // create random presId 
   var presId = Math.random().toFixed(6).substr(2);
-  navigator.presentation.startSession(presUrl, presId).then(function(newSession){
-    // a new session is started successfully
-    setSession(newSession);
-  },function(){
+  // Start new session. presId is optional.
+  // the new started session will be passed to setSession on success or null on error
+  navigator.presentation.startSession(presUrl, presId).then(setSession).catch(function(e){
     // user cancels the selection dialog or an error is occurred
     setSession(null);
   });
 &lt;/script&gt;
-
-
 </pre>
       </section>
       <section>
@@ -660,17 +657,13 @@ <h3 id="joining-a-presentation-session-example"><span class="secno">5.3 </span>
 &lt;script&gt;
   // read presId from localStorage if exists 
   var presId = localStorage &amp;&amp; localStorage["presId"] || null;
-  // presId is mandatory for joinSession
-  presId &amp;&amp; navigator.presentation.joinSession(presUrl, presId).then(function(existingSession){
-    // session with requested presUrl and presId is found and joined successfully
-    setSession(existingSession);
-  },function(){
-    // no session found for presUrl and presId or error is occurred 
+  // presId is mandatory for joinSession.
+  // The joined session will be passed to setSession on success or null on error
+  presId &amp;&amp; navigator.presentation.joinSession(presUrl, presId).then(setSession).catch(function(e){
+    // no session found for presUrl and presId or an error is occurred
     setSession(null);
   });
 &lt;/script&gt;
-
-
 </pre>
       </section>
       <section>
@@ -704,8 +697,6 @@ <h3 id="monitor-session's-state-and-exchange-data-example"><span class="secno">5
     }
   };
 &lt;/script&gt;
-
-
 </pre>
         <pre class="example">&lt;!-- presentation.html --&gt;
 &lt;script&gt;
@@ -719,8 +710,6 @@ <h3 id="monitor-session's-state-and-exchange-data-example"><span class="secno">5
       session.postMessage("hello");
   };
 &lt;/script&gt;
-
-
 </pre>
       </section><!--
       <p>