Add initial jtex workflow, template, and documentation for Cours 4.0

.forgejo/workflows/jtex.yml

@@ -0,0 +1,15 @@
+name: jtex
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+jobs:
+  test:
+    name: test template.yml
+    runs-on: self-hosted
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+      - run: npm install -g jtex
+      - run: jtex check