Add message about JS SDK v2 end-of-support (#4596)

Author: trivikr

doc-src/templates/default/layout/html/layout.erb

@@ -20,7 +20,7 @@
       </div>
 
       <div id="content">
-        <%= erb(:v3note) %>
+        <%= erb(:v2note) %>
         <!--REGION_DISCLAIMER_DO_NOT_REMOVE-->
         <%= yieldall %>
       </div>

doc-src/templates/default/layout/html/v2note.erb

@@ -0,0 +1,13 @@
+<div class="alert alert-info">
+	<div class="alert-icon"></div>
+	<div>
+		<div class="alert-header">
+      We <a href"https://aws.amazon.com/blogs/developer/announcing-end-of-support-for-aws-sdk-for-javascript-v2">announced</a> the upcoming
+      end-of-support for AWS SDK for JavaScript v2.
+    </div>
+		<div class="alert-content">
+      We recommend that you migrate to <a href="https://docs.aws.amazon.com/sdk-for-javascript/v3/developer-guide/welcome.html">AWS SDK for JavaScript v3</a>.
+      For dates, additional details, and information on how to migrate, please refer to the linked announcement.
+		</div>
+	</div>
+</div>