Removed $ from the commands in Readme (#416)

* Update README.md

* Update README.md

* Update README.md

* Update README.md

* Update README.md

---------

Co-authored-by: Daichi Furiya <[email protected]>

Author: AbhishekDoshi26

README.md

@@ -61,15 +61,15 @@ Widget build(BuildContext context) {
 Works with macOS and Linux.
 
 ```sh
-$ brew install FlutterGen/tap/fluttergen
+brew install FlutterGen/tap/fluttergen
 ```
 
 ### Pub Global
 
 Works with macOS, Linux and Windows.
 
 ```sh
-$ dart pub global activate flutter_gen
+dart pub global activate flutter_gen
 ```
 
 You might need to [set up your path](https://dart.dev/tools/pub/cmd/pub-global#running-a-script-from-your-path).
@@ -87,23 +87,23 @@ dev_dependencies:
 2. Install [FlutterGen]
 
 ```sh
-$ flutter pub get
+flutter pub get
 ```
 
 3. Use [FlutterGen]
 
 ```
-$ flutter packages pub run build_runner build
+flutter packages pub run build_runner build
 ```
 
 ## Usage
 
 Run `fluttergen` after the configuration [`pubspec.yaml`](https://dart.dev/tools/pub/pubspec).
 
 ```sh
-$ fluttergen -h
+fluttergen -h
 
-$ fluttergen -c example/pubspec.yaml
+fluttergen -c example/pubspec.yaml
 ```
 
 ## Configuration file