Usage instructions in README.

README.md

@@ -1,2 +1,46 @@
-# docker-select-image-pull
+# Pre-pull Docker Compose Selectively Service Images Action
 
+## 🚀 Overview
+
+When running `docker compose --dry-run`, image pulls are only simulated which can cause the dry-run to fail since no actual images are pulled. This action **pre-pull images for services in Docker Compose selectively in parallel** rather than pulling images for every single defined service in a Compose file.
+
+## 🛠️ Inputs
+
+| Input             | Required | Default | Description                                                               |
+| ----------------- | -------- | ------- | ------------------------------------------------------------------------- |
+| `services`        | ✅       | —       | Space or new-line separated list of Docker Compose service names to pull. |
+| `compose_profile` | ❌       | `""`    | Docker Compose profile to use. Optional.                                  |
+| `env_file`        | ❌       | `.env`  | Path to `.env` file for Docker Compose.                                   |
+
+---
+
+## 📖 Usage
+
+### Example 1
+
+```yaml
+---
+steps:
+  - name: Checkout repository
+    uses: actions/checkout@v4
+
+  - name: Pre-pull service images
+    uses: https://git.trez.wtf/Trez/docker-select-image-pull@main
+    with:
+      services: "web db"
+```
+
+### Example 2
+
+```yaml
+steps:
+  - name: Checkout repository
+    uses: actions/checkout@v4
+
+  - name: Pre-pull service images
+    uses: https://git.trez.wtf/Trez/docker-select-image-pull@main
+    with:
+      services: |
+        web
+        db
+```