Update landing page secondary CTA (#2678)

* Update landing page secondary CTA

* update registration link

* Update src/Elastic.Markdown/Layout/_LandingPage.cshtml

Co-authored-by: Kaarina Tungseth <kaarina.tungseth@elastic.co>

---------

Co-authored-by: Felipe Cotti <felipe.cotti@elastic.co>
Co-authored-by: Kaarina Tungseth <kaarina.tungseth@elastic.co>

Author: 3 people

src/Elastic.Documentation.Site/_static/hero.png

@@ -13,8 +13,8 @@
 					<a href="@Model.Link("/get-started")" class="grow select-none cursor-pointer text-white text-nowrap bg-blue-elastic hover:bg-blue-elastic-110 focus:ring-4 focus:ring-blue-elastic-50 font-semibold font-sans rounded-sm px-6 py-2 focus:outline-none h-10 flex items-center justify-center">
 						Elastic Fundamentals
 					</a>
-					<a href="@Model.Link("/deploy-manage/upgrade")" class="grow cursor-pointer text-blue-elastic hover:text-blue-elastic-100 text-nowrap border-2 border-blue-elastic hover:border-blue-elastic-100 focus:ring-4 focus:outline-none focus:ring-blue-elastic-50 font-semibold font-sans rounded-sm px-6 py-2 text-center h-10 flex items-center justify-center">
-						Upgrade versions
+					<a href="https://cloud.elastic.co/registration?page=docs&placement=docs-body" class="grow cursor-pointer text-blue-elastic hover:text-blue-elastic-100 text-nowrap border-2 border-blue-elastic hover:border-blue-elastic-100 focus:ring-4 focus:outline-none focus:ring-blue-elastic-50 font-semibold font-sans rounded-sm px-6 py-2 text-center h-10 flex items-center justify-center">
+						Start free trial
 					</a>
 				</div>
 				@if (Model.AllVersionsUrl is not null)