;ci:docker: trigger manually [#2002]

.github/workflows/docker.yml

@@ -1,12 +1,14 @@
-name: Docker images
+# TRIGGER: Runs on any push to the docker branch.
+# ACTION: Generates docker images for linux x64 and arm64, and pushes them to Github's Container Registry.
+# Experimental, see https://github.com/simonmichael/hledger/pull/2002.
+
+name: docker
 
 on:
   push:
     branches:
-      - build-docker
-      - master
-    tags:
-      - '*.*.*'
+      - docker
+  workflow_dispatch:
 
 permissions:
   contents: read