update readme

Author: justrdk

README.md

@@ -1,3 +1,48 @@
-## Update Json File action
+# GitHub Action - Update JSON File
+This GitHub Action edits the provided fields on a provided JSON file
 
-This action will update any json fields from a file to the provided values
+## Usage
+
+Add this step in your workflow file
+```yaml
+- name: Update my-file.json description
+  uses: restack/[email protected]
+  with:
+    file: my-file.json
+    fields: "{'a.b.c': 'value_here', 'a.b.d[0]': 'value_here'}"
+```
+
+### Input Variables
+
+- `file`: File name/path to edit. e.g `package.json`
+- `fields`: Fields to edit. can be nested fields. example: `{'a.b.c[0]': 'value_here', 'z.x': 'value_here'}`
+
+
+#### Example - Updating `package.json` Version
+
+```yaml
+name: Build and Release
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+env:
+  GITHUB_TOKEN: ${{ github.token }}
+
+jobs:
+  build:
+    name: Build and Release
+    runs-on: ubuntu-latest
+    steps:
+    - name: Checkout code
+    - uses: actions/checkout@v3
+ 
+    - name: Update package.json version
+      uses: jossef/[email protected]
+      with:
+        file: package.json
+        fields: "{'version': '1.2.4'}"
+```