removing public images from internal location

Reviewed-by: gtema <artem.goncharov@gmail.com>
Co-authored-by: Hasko, Vladimir <vladimir.hasko@t-systems.com>
Co-committed-by: Hasko, Vladimir <vladimir.hasko@t-systems.com>

otc_metadata/data/services.yaml

@@ -656,7 +656,7 @@ documents:
     service_type: ims
     title: Developer Guide
     type: dev
-  - html_location: docs/ims/public-images
+  - environment: public
     link: /image-management-service/public-images/
     pdf_name: ims-public-images
     rst_location: doc/public-images/source