Add image-url to the output of the action.

Added Complete URL to the Output of the action.
Such that other steps can use the URL for further operations
also, Modified README based on the changes.

Signed-off-by: divyansh42 <diagrawa@redhat.com>

README.md

@@ -55,6 +55,12 @@ Push-to-registry is a GitHub Action for pushing an OCI-compatible image to an im
   </tr>
 </table>
 
+## Action Outputs
+
+This action produces these outputs which can be used for further processing in different Github action:
+
+**image-url**: Contains complete URL of the image which is pushed using this action. (e.g. `quay.io/username/spring-image:v1`)
+
 ## Examples
 
 The example below shows how the `push-to-registry` action can be used to push an image created by the [`buildah-action`](https://github.com/redhat-actions/buildah-action) in an early step.

action.yml

@@ -21,6 +21,9 @@ inputs:
   password:
     description: 'Password to use as credential to authenticate to the registry'
     required: true
+outputs:
+  image-url:
+    description: 'Complete URL of the pushed image'
 runs:
   using: 'node12'
   main: 'dist/index.js'

src/index.ts

@@ -40,6 +40,8 @@ export async function run(): Promise<void> {
         return Promise.reject(new Error(push.reason));
     }
     core.info(`Successfully pushed ${imageToPush} to ${registryUrl}.`);
+    
+    core.setOutput('image-url', registryUrl);
 }
 
 async function execute(executable: string, args: string[]): Promise<CommandResult> {