github: expect docker tag to include -beta suffix

Author: guggero

.github/workflows/docker.yml

@@ -32,12 +32,12 @@ jobs:
       - name: Set env for RELEASE_VERSION
         run: echo "RELEASE_VERSION=${GITHUB_REF#refs/*/docker}" >> $GITHUB_ENV
 
-      # We will push tags with the format docker/v0.x.y-lnd-v0.aa.bb-beta where
-      # x and y are lndinit's version and aa and bb are lnd's version. This
-      # variable LND_VERSION extracts everything after v0.x.y-lnd- so we know
-      # which base image we need to build on top of.
+      # We will push tags with the format docker/v0.x.y-beta-lnd-v0.aa.bb-beta
+      # where x and y are lndinit's version and aa and bb are lnd's version.
+      # This variable LND_VERSION extracts everything after v0.x.y-lnd- so we
+      # know which base image we need to build on top of.
       - name: Set env for LND_VERSION
-        run: echo "LND_VERSION=${RELEASE_VERSION##v*\.*\.*-lnd-}" >> $GITHUB_ENV
+        run: echo "LND_VERSION=${RELEASE_VERSION##v*\.*\.*-beta-lnd-}" >> $GITHUB_ENV
 
       - name: Build and push
         id: docker_build