Update content/reference/api/registry/_index.md

Co-authored-by: Sarah Sanders <[email protected]>

Author: craig-osterhout

content/reference/api/registry/_index.md

@@ -113,7 +113,7 @@ before fetching layers.
 
 ### Check existing manifests
 
-The image manifest can be checked for existence with the following URL:
+Check for existing manifests with the following URL:
 
 ```text
 HEAD /v2/<name>/manifests/<reference>