ci: add release action

.github/workflows/release.yaml

@@ -0,0 +1,30 @@
+name: release
+
+on:
+  push:
+    tags:
+      - "v*"
+  workflow_dispatch:
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@master
+      - uses: docker-practice/actions-setup-docker@master
+      - uses: actions-rs/toolchain@v1
+        with:
+          target: x86_64-unknown-linux-gnu
+      - name: Install cross
+        run: |
+          sudo apt update
+          sudo apt install build-essential upx-ucl -y
+          cargo install cross
+      - name: Cross build
+        run: |
+          cross build --target x86_64-unknown-linux-gnu --release
+          cross build --target x86_64-pc-windows-gnu --release
+      - name: Compress binaries
+        run: |
+          upx --best target/x86_64-unknown-linux-gnu/release/mdbook-embedify
+          upx --best target/x86_64-pc-windows-gnu/release/mdbook-embedify.exe