Update index fix migration link.mdx (#1768)

Co-authored-by: Anna Wen <[email protected]>

Author: oliviaflory

src/pages/index.mdx

@@ -43,7 +43,7 @@ export default HomepageTemplate;
     <ImageCard
       title="Migration guide"
       aspectRatio="1:1"
-      href="https://github.com/carbon-design-system/carbon-for-ibm-dotcom/blob/release/v2.0.0/docs/dotcom-v2-migration.md"
+      href="https://github.com/carbon-design-system/carbon-for-ibm-dotcom/blob/main/docs/dotcom-v2-migration.md"
       actionIcon="launch"
       titleColor="dark"
       subTitleColor="dark"