Update README with two-step usage pattern (restore before build, save after)

README.md

@@ -23,6 +23,13 @@ A Gitea Action that caches build files as `tar.xz` archives on the runner filesy
 2. Stores archives at `~/.cache/.cache-store/<key>.tar.xz`
 3. Restores by extracting the archive to `/`, saves by creating one
 
+## Usage
+
+This action must be used **twice** in your workflow:
+
+1. **Before build** — restores cache if it exists
+2. **After build** — saves the cache archive (only on cache miss)
+
 ## Rust Example
 
 ```yaml
@@ -38,13 +45,24 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
+
+      # 1. Restore cache before build
+      - uses: Actions/Cache@main
+        id: cache
+        with:
+          key-prefix: 'cargo-registry'
+          key-file: 'Cargo.lock'
+          path: '~/.cargo/registry'
+
+      - name: Build
+        run: cargo build --release
+
+      # 2. Save cache after build
       - uses: Actions/Cache@main
         with:
           key-prefix: 'cargo-registry'
           key-file: 'Cargo.lock'
           path: '~/.cargo/registry'
-      - name: Build
-        run: cargo build --release
 ```
 
 ## Skip Steps on Cache Hit
@@ -62,15 +80,26 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
+
+      # 1. Restore cache
       - uses: Actions/Cache@main
         id: cache
         with:
           key-prefix: 'rust'
           key-file: 'Cargo.lock'
           path: '~/.cargo/registry'
+
       - name: Fetch dependencies
         if: steps.cache.outputs.cache-hit != 'true'
         run: cargo fetch
+
       - name: Build
         run: cargo build --release
+
+      # 2. Save cache
+      - uses: Actions/Cache@main
+        with:
+          key-prefix: 'rust'
+          key-file: 'Cargo.lock'
+          path: '~/.cargo/registry'
 ```