Ship Docker image also to GHCR.io (#29240)

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

.github/workflows/docker.yaml

@@ -1,4 +1,4 @@
-name: Dockerhub
+name: Docker
 on:
     workflow_dispatch: {}
     push:
@@ -37,12 +37,20 @@ jobs:
                   username: ${{ secrets.DOCKERHUB_USERNAME }}
                   password: ${{ secrets.DOCKERHUB_TOKEN }}
 
+            - name: Login to GitHub Container Registry
+              uses: docker/login-action@9780b0c442fbb1117ed29e0efdff1e18412f7567 # v3
+              with:
+                  registry: ghcr.io
+                  username: ${{ github.repository_owner }}
+                  password: ${{ secrets.GITHUB_TOKEN }}
+
             - name: Docker meta
               id: meta
               uses: docker/metadata-action@369eb591f429131d6889c46b94e711f089e6ca96 # v5
               with:
                   images: |
                       vectorim/element-web
+                      ghcr.io/element-hq/element-web
                   tags: |
                       type=ref,event=branch
                       type=ref,event=tag

.github/workflows/release.yml

@@ -50,7 +50,7 @@ jobs:
         permissions:
             checks: read
         steps:
-            - name: Wait for dockerhub
+            - name: Wait for docker build
               uses: t3chguy/wait-on-check-action@18541021811b56544d90e0f073401c2b99e249d6 # fork
               with:
                   ref: master

docs/release.md

@@ -128,7 +128,7 @@ flowchart TD
 
     subgraph Deploying
         D1[\Deploy staging.element.io/]
-        D2[\Check dockerhub/]
+        D2[\Check docker build/]
         D3[\Deploy app.element.io/]
         D4[\Check desktop package/]
 
@@ -213,10 +213,10 @@ switched back to the version of the dependency from the master branch to not lea
 # Deploying
 
 We ship the SDKs to npm, this happens as part of the release process.
-We ship Element Web to dockerhub, `*.element.io`, and packages.element.io.
+We ship Element Web to dockerhub, ghcr.io, `*.element.io`, and packages.element.io.
 We ship Element Desktop to packages.element.io.
 
-- [ ] Check that element-web has shipped to dockerhub
+- [ ] Check that element-web has shipped to dockerhub & ghcr.io
 - [ ] Check that the staging [deployment](https://github.com/element-hq/element-web/actions/workflows/deploy.yml) has completed successfully
 - [ ] Test staging.element.io