Add Github workflow to build docker (#397)

Author: tbarsballe

.github/workflows/docker.yml

@@ -0,0 +1,18 @@
+name: docker
+
+on:
+  pull_request:
+    paths:
+      - 'planet-notebook-docker/**'
+
+jobs:
+  build:
+    name: Build Docker
+    runs-on: ubuntu-latest
+    steps:
+    - name: Checkout code
+      uses: actions/checkout@v5
+    - name: Build Image
+      run: |
+        docker build -t planet-notebooks planet-notebook-docker/
+

planet-notebook-docker/Dockerfile

@@ -1,5 +1,5 @@
 # 2025-09-15 build
-# https://github.com/jupyter/docker-stacks/wiki/minimal-notebook-414b5d749704
+# https://jupyter-docker-stacks.readthedocs.io/en/latest/using/selecting.html#jupyter-minimal-notebook
 FROM quay.io/jupyter/minimal-notebook:8515ad39f045
 
 # Copy requirements file for package installation