ICU-22606 Create full release from CI - review feedback

Author: mihnita

.github/README.md

@@ -1,5 +1,10 @@
 ## How to create a Fedora docker image
 
+For the general process and concepts see:
+https://docs.github.com/en/packages/working-with-a-github-packages-registry/working-with-the-container-registry
+
+For our case I replaced the generic names with our own owner / repo / names / etc.
+
 Run
 ```
 docker login ghcr.io
@@ -8,18 +13,26 @@ docker login ghcr.io
 When prompted use these:
 
 * **User:** the github user
-* **Password:** the github key
+* **Password:** the github token
 
 Update the timestamp (`20240929`) with the current date, ISO style:
 ```
 docker build --tag ghcr.io/unicode-org/fedora-docker-gcr:20240929 -f Dockerfile_fedora .
 docker push ghcr.io/unicode-org/fedora-docker-gcr:20240929
 ```
 
-See:
+For more info see:
 https://docs.github.com/en/actions/use-cases-and-examples/publishing-packages/publishing-docker-images
 
-Also:
+and:
 https://stackoverflow.com/questions/64033686/how-can-i-use-private-docker-image-in-github-actions
 
 To consider: generate and publish the docker image from a GitHub action.
+
+---
+
+The `DOCKER_CONTAINER_USER_NAME` and `DOCKER_CONTAINER_REGISTRY_TOKEN` used
+in the action file for user and password are secrets already created.
+
+They can be any GitHub user + token with the proper access rights.
+Right now this is a token of the icu-robot account.