Accessibility updates - main landmark roles (#17106)

* Removed multiple main tags from home page

Signed-off-by: chaitanyakaranam <chaitanya.karanam@yahoo.com>

* Removed multiple occurances of main in case-studies page

Signed-off-by: chaitanyakaranam <chaitanya.karanam@yahoo.com>

* Replaced css for main tag with .main-section class

Signed-off-by: ChaitanyaKaranam <karanam.krishna.25@gmail.com>

* Added main landmark role for all the pages

Signed-off-by: ChaitanyaKaranam <karanam.krishna.25@gmail.com>

* Force checks.

request-checks: true

content/en/partners/_index.html

@@ -7,7 +7,7 @@ cid: partners
 ---
 
 <section id="users">
-    <main>
+    <main class="main-section">
         <h5>Kubernetes works with partners to create a strong, vibrant codebase that supports a spectrum of complementary platforms.</h5>
         <div class="col-container">
           <div class="col-nav">