Update README.md How to build wasmtime-c-api

README.md

@@ -131,16 +131,17 @@ Next up you'll want to have a [local Wasmtime build
 available](https://bytecodealliance.github.io/wasmtime/contributing-building.html).
 
 You'll need to build at least the `wasmtime-c-api` crate, which, at the time of
-this writing, would be:
+this writing, would be (apple m1 example):
 
 ```sh
-$ cargo build -p wasmtime-c-api
+$ rustup target add aarch64-apple-darwin
+$ cargo build --release --target aarch64-apple-darwin  -p wasmtime-c-api
 ```
 
-Once you've got that you can set up the environment of this library with:
+Once you've got that you can set up the environment of this library with (apple m1 example):
 
 ```sh
-$ ./ci/local.sh /path/to/wasmtime
+$ ./ci/local.sh /path/to/wasmtime aarch64-apple-darwin
 ```
 
 This will create a `build` directory which has the compiled libraries and header

ci/local.sh

@@ -1,6 +1,7 @@
 #!/bin/bash
 
 wasmtime=$1
+target=$2
 if [ "$wasmtime" = "" ]; then
   echo "must pass path to wasmtime"
   exit 1
@@ -15,9 +16,9 @@ for d in "include" "include/wasmtime" "linux-x86_64" "macos-x86_64" "windows-x86
   echo "package ${name/-/_}" > "$path/empty.go"
 done
 
-build="$wasmtime/target/release"
+build="$wasmtime/target/"$target"/release"
 if [ ! -d "$build" ]; then
-  build="$wasmtime/target/debug"
+  build="$wasmtime/target/"$target"/debug"
 fi
 # Use absolute path for symbolic links
 build=$(cd "$build" && pwd)