Add canonical link to 2.14 index page (#7573)

Signed-off-by: Fanit Kolchina <[email protected]>
(cherry picked from commit 2e75929)
Signed-off-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

index.md

@@ -6,6 +6,7 @@ redirect_from: /404.html
 has_children: false
 nav_exclude: true
 permalink: /
+canonical_url: https://opensearch.org/docs/latest/
 ---
 
 {% include banner.html %}