Update ext/README.md

Addressed the comment for indicating that the extension definitions applies to the layout of the spec

Signed-off-by: mnltejaswini <mnl.tejaswini@gmail.com>
Co-authored-by: Stephen Day <stevvooe@users.noreply.github.com>
Signed-off-by: Vincent Batts <vbatts@hashbangbash.com>

ext/README.md

@@ -52,7 +52,7 @@ As of current, ```_oci``` and ```_ext``` are considered as reserved namespaces a
 
 ## Filename
 
-Extension definitions SHOULD be placed under `./ext/`. Extension files
+Extension definitions SHOULD be placed under `./ext/` in the specification repository. Extension files
 SHOULD follow the `ext-$ns-$name.md`. Refer [ext.md](./ext.md) for more details.
 
 ## Detail