fix(readme): Update readme to clarify usage of searchable fields retrieval

readme.md

@@ -203,7 +203,7 @@ class Product extends SmartDataDbDoc<Product, Product> {
 }
 
 // List searchable fields
-const searchableFields = getSearchableFields('Product');
+const searchableFields = Product.getSearchableFields();
 
 // 1: Exact phrase across all fields
 await Product.search('"Kindle Paperwhite"');
@@ -230,7 +230,7 @@ await Product.search('');
 The search functionality includes:
 
 - `@searchable()` decorator for marking fields as searchable
-- `getSearchableFields()` to list searchable fields for a model
+- `Class.getSearchableFields()` static method to list searchable fields for a model
 - `search(query: string)` method supporting:
   - Exact phrase matches (`"my exact string"` or `'my exact string'`)
   - Field‑scoped exact & wildcard searches (`field:value`, `field:Air*`)