Add workflow for mirroring this repo on the ICL org

Closes #9.

.github/workflows/sync-mirror.yml

@@ -0,0 +1,23 @@
+on:
+  push:
+  workflow_dispatch:
+
+jobs:
+  my_job:
+    if: github.repository == 'djmaxus/matlab-repo-init.git'
+    runs-on: ubuntu-latest
+    steps:
+      - uses: webfactory/ssh-agent@v0.9.0
+        with:
+          ssh-private-key: ${{ secrets.SSH_PRIVATE_KEY }}
+      - name: Push changes to ImperialCollegeLondon/matlab-repo-init
+        run: |
+          # Clone and check out this repo
+          git clone --mirror git@github.com:djmaxus/matlab-repo-init.git
+          cd matlab-repo-init.git
+
+          # Add repo in Imperial's org as remote
+          git remote add icl git@github.com:ImperialCollegeLondon/matlab-repo-init.git
+
+          # Push all branches, overwriting if necessary
+          git push icl --all --force