updated README to include helper script decumentation

README.md

@@ -34,6 +34,22 @@ docker buildx build --build-arg TARGETS=${TARGETS} -t <your_username>/<your_tag>
 --platform ${TARGETS} . --push
 ```
 
+Or 
+4. use the helper script make.bash as follows
+```bash
+# optional, choose targets (defaults to the following list)
+export TARGETS="linux/amd64,linux/386,linux/arm64,linux/arm/v7,linux/arm/v6"
+
+# optional, choose psiphon version (defaults to the lastest committed docker image)
+export VERSION=2.0.30
+
+# optional, choose go version (currently 1.20)
+export GO_VERSION=1.20
+
+# run the script
+./make.bash
+```
+
 Build-args available
 |build-arg|default|Description|
 |--|--|--|