update readme

README.md

@@ -2,7 +2,7 @@
 
 This action is to compute the SHA256 hash of specified files.
 
-**NOTE:** This action is written in Go. Please make sure the `runs-on` runner supports running Go actions.
+**NOTE:** This action is written in Go. Please setup the Go environment before running this action or make sure the `runs-on` runner supports running Go actions.
 
 ## Usage
 
@@ -27,6 +27,11 @@ This action is to compute the SHA256 hash of specified files.
 
 ## Example
 ``` yml
+# Setup the Go environment. This step can be skipped if Go has been installed.
+- uses: actions/setup-go@v3
+  with:
+    go-version: '1.20'
+
 - uses: actions/go-hashfiles@v0.0.1
   id: get-hash
   with: 
@@ -34,6 +39,7 @@ This action is to compute the SHA256 hash of specified files.
       go.sum
       ./admin/*
       **/package-lock.json
+
 - name: Echo hash
   run: echo ${{ steps.get-hash.outputs.hash }}
 ```