Accessibility Updates (#16633)

* Fixed accessibility issues in home page

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

* Fixed accessibility issues for docs/home page

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

* Fixed accessibility issues for /partners page

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

* Fixed accessibility issues for /community page

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

* Update layouts/partials/header.html

Co-Authored-By: Tim Bannister <tim@scalefactory.com>

* Update layouts/partials/footer-scripts.html

Co-Authored-By: Tim Bannister <tim@scalefactory.com>

* Update layouts/index.html

Co-Authored-By: Tim Bannister <tim@scalefactory.com>

* Update content/en/partners/_index.html

Co-Authored-By: Tim Bannister <tim@scalefactory.com>

* Update content/en/community/_index.html

Co-Authored-By: Tim Bannister <tim@scalefactory.com>

* Added missing quotes

* Added landmark roles for search bar and footer

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

* Changed images alt text

Changed alt text from 'kubernetes community' to 'Kubernetes Conference Gallery'

* Removed verb from iframe title

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

* Change alt text for GitHub image

Co-Authored-By: Tim Bannister <tim@scalefactory.com>

* Few alt text changes

* Modified alt text

layouts/partials/docs/top-menu.html

@@ -15,7 +15,7 @@
 		<li><a href="{{ .RelPermalink }}"{{ if $yah }} class="YAH"{{ end }}>{{ .LinkTitle | upper }}</a></li>
 		{{ end }}
 	</ul>
-	<form id="searchBox" action="/docs/search/">
+	<form id="searchBox" action="/docs/search/" role="search">
 		<input type="text" id="search" name="q" placeholder="{{ T "ui_search_placeholder" }}" aria-label="Search">
 	</form>
 </div>