Created exercises

- Added endpoint to retrieve the list of exercises

routes/api.php

@@ -17,3 +17,7 @@ use Illuminate\Support\Facades\Route;
 Route::middleware('auth:api')->get('/user', function (Request $request) {
     return $request->user();
 });
+
+Route::prefix('exercises')->group(function () {
+    Route::get('', 'ExerciseController@index');
+});