Add README.md and Makefile

Makefile

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+lint:
+	./bin/ameba
+
+lint-fix:
+	./bin/ameba --fix
+
+build:
+	crystal build src/main.cr
+
+test:
+	crystal spec

README.md

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+# crystal-devcontainer-template
+
+This is a template repo for creating a new Crystal project with DevPod using devcontainers.
+
+# Usage
+
+## Create New Project from Template
+
+1. **On GitHub**: Click "Use this template" → "Create a new repository"
+2. **Name your new repo** and clone it locally:
+```bash
+git clone https://github.com/yourusername/your-new-project.git
+cd your-new-project
+```
+
+## Update Project Files
+
+3. **Replace placeholder strings** in these files:
+   - ```.devcontainer/devcontainer.json```: ```PROJECT_NAME``` → ```your-new-project```
+   - ```shard.yml```: ```PROJECT_NAME```, ```YOUR_NAME```, ```YOUR_EMAIL```
+   - ```src/main.cr```: ```PROJECT_NAME``` → ```your-new-project```
+
+4. **Quick find/replace** (Linux/Mac):
+```bash
+find . -type f -name "*.json" -o -name "*.yml" -o -name "*.cr" | xargs sed -i 's/PROJECT_NAME/your-new-project/g'
+find . -type f -name "*.yml" | xargs sed -i 's/YOUR_NAME/Your Name/g'
+find . -type f -name "*.yml" | xargs sed -i 's/YOUR_EMAIL/your@email.com/g'
+```
+
+## Start DevPod
+
+5. **Open with DevPod**:
+```bash
+devpod up . --provider docker
+```
+
+6. **Connect with Zed**:
+```bash
+devpod ssh . --command "code-server --bind-addr 0.0.0.0:8080"
+```
+Then connect Zed to the running container.
+
+## Initialize Crystal Project
+
+7. **Inside the devcontainer**:
+```bash
+shards install
+crystal build src/main.cr
+./main
+```