[process] cleaned up README for ch02/hello_world project + added github actions to auto publish multi-arch images

Signed-off-by: danbugs <[email protected]>

[fix] move gh workflow to workflows/ folder

Signed-off-by: danbugs <[email protected]>

[fix] change hello_world_host dockerfile path in gh actions

Signed-off-by: danbugs <[email protected]>

[fix] change hello_world_host dockerfile path in gh actions

Signed-off-by: danbugs <[email protected]>

Author: danbugs

.github/workflows/publish-ghcr-images.yaml

@@ -0,0 +1,39 @@
+name: Build and Push Multi-Arch Images to GHCR
+
+on:
+  push:
+    branches:
+      - main
+
+permissions:
+  packages: write
+  contents: read
+
+jobs:
+  build-and-push:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Log in to GitHub Container Registry
+        uses: docker/login-action@v3
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GHCR_PAT }}
+
+      - name: Build and Push hello_world_host
+        uses: docker/build-push-action@v5
+        with:
+          context: chapter02/hello_world
+          file: chapter02/hello_world/Dockerfile
+          push: true
+          tags: ghcr.io/${{ github.repository }}/hello-world-host:latest
+          platforms: linux/amd64,linux/arm64
+          cache-from: type=gha
+          cache-to: type=gha,mode=max
+

Cargo.lock

@@ -3,26 +3,19 @@
 ## How to build the guest?
 
 ```bash
+# from the `hello_world_guest/` directory
 cargo build --target wasm32-unknown-unknown --release
 ```
 
 ## How to run the host?
 
 ```bash
-docker run --rm -v <absolute-path-to-the-directory-containing-the-wasm-module>:/data danstaken/hello_world_host:latest /data/hello_world_guest.wasm 'Dan'
-# for me, it is: docker run --rm -v C:\Users\danil\source\repos\serverside-wasm-book-code\chapter02\hello_world\hello_world_guest:/data danstaken/hello_world_host:latest /data/hello_world_guest.wasm 'Dan'
+docker run --rm -v "$(pwd):/data" danstaken/hello_world_host:latest  /data/hello_world_guest.wasm 'Dan'
 ```
 
 You can also run locally, with:
 
 ```bash
-# from `hello_world_host` directory
+# from the `hello_world_host/` directory
 cargo run -- ../hello_world_guest/hello_world_guest.wasm 'Dan'
-```
-
-## Toolchain versions
-
-```bash
-cargo 1.79.0 (ffa9cf99a 2024-06-03)
-Docker version 24.0.7, build afdd53b
 ```