docs(readme): add section for configuring custom headers in Strapi client

README.md

@@ -38,6 +38,7 @@
    - [Basic Configuration](#basic-configuration)
    - [Authentication](#authentication)
      - [API Token Authentication](#api-token-authentication)
+     - [Custom Headers](#custom-headers)
 3. [API Reference](#-api-reference)
 4. [Resource Managers](#-resource-managers)
    - [`.collection()`](#collectionresource)
@@ -118,6 +119,50 @@ const client = strapi({
 });
 ```
 
+#### Custom Headers
+
+You can configure custom headers to be included with every request made by the client:
+
+```typescript
+const client = strapi({
+  baseURL: 'http://localhost:1337/api',
+  auth: 'your-api-token-here',
+  headers: {
+    'X-Custom-Header': 'value',
+    'Accept-Language': 'en-US',
+  },
+});
+```
+
+**Header Precedence:**
+
+- Custom headers specified in the client configuration are applied to all requests
+- Authentication headers (e.g., `Authorization` from API tokens) take precedence over custom headers
+- Headers specified in individual requests (e.g., in `fetch()` calls) take precedence over both custom and authentication headers
+
+**Example: Using Custom Headers**
+
+```typescript
+// Initialize client with custom headers
+const client = strapi({
+  baseURL: 'http://localhost:1337/api',
+  headers: {
+    'X-Request-ID': '12345',
+    'Accept-Language': 'en-US',
+  },
+});
+
+// Headers will be included in all requests
+const articles = await client.collection('articles').find();
+
+// Override headers for a specific request
+const article = await client.fetch('/articles/1', {
+  headers: {
+    'Accept-Language': 'fr-FR', // This will override the client-level header
+  },
+});
+```
+
 ## 📚 API Reference
 
 The Strapi client library instance provides key properties and utility methods for content and API interaction: