dot instead of source; readme

Dockerfile

@@ -9,7 +9,7 @@ RUN apt install -y g++-mingw-w64-x86-64 \
 	g++-aarch64-linux-gnu libc6-dev-arm64-cross
 
 RUN curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y
-RUN source "$HOME/.cargo/env"
+RUN . "$HOME/.cargo/env"
 
 ENV CARGO_TARGET_ARMV7_UNKNOWN_LINUX_GNUEABIHF_LINKER=arm-linux-gnueabihf-gcc \
 	CC_armv7_unknown_Linux_gnueabihf=arm-linux-gnueabihf-gcc \

readme.md

@@ -0,0 +1,34 @@
+
+Container image with Node20 and Rust, primarily for CI Rust build steps
+
+---
+
+```yaml
+name: Build
+
+on:
+  push:
+    branches:
+    - master
+  pull_request:
+    branches:
+    - master
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    container:
+      image: gitea.jbrumond.me/images/rust-ci:latest
+    strategy:
+      matrix:
+        rust-target:
+        - x86_64-pc-windows-gnu
+        - armv7-unknown-linux-gnueabihf
+        - aarch64-unknown-linux-gnu
+    steps:
+      - name: Check out the repo
+        uses: actions/checkout@v3
+
+      - name: Build
+        run: cargo build --target ${{ matrix.rust-target }}
+```