feat(README): restore some of the content

README.md

@@ -1,5 +1,23 @@
+<h1 align="center">
+
+   [![Sinch Logo](https://developers.sinch.com/static/logo-07afe977d6d9dcd21b066d1612978e5c.svg)](https://www.sinch.com)
+
+   Python SDK
+
+   [![License](https://img.shields.io/badge/License-Apache_2.0-blue.svg)](https://github.com/sinch/sinch-sdk-python/blob/main/LICENSE)
+
+
+   [![Python 3.9](https://img.shields.io/badge/python-3.9-blue.svg)](https://www.python.org/downloads/release/python-390/)
+   [![Python 3.10](https://img.shields.io/badge/python-3.10-blue.svg)](https://www.python.org/downloads/release/python-3100/)
+   [![Python 3.11](https://img.shields.io/badge/python-3.11-blue.svg)](https://www.python.org/downloads/release/python-3110/)
+   [![Python 3.12](https://img.shields.io/badge/python-3.12-blue.svg)](https://www.python.org/downloads/release/python-3120/)
+
+
+</h1>
+
 # Sinch Python SDK
 
+
 Here you'll find documentation related to the Sinch Python SDK, including how to install it, initialize it, and start developing Python code using Sinch services.
 
 To use Sinch services, you'll need a Sinch account and access keys. You can sign up for an account and create access keys at [dashboard.sinch.com](https://dashboard.sinch.com).
@@ -122,6 +140,30 @@ except NumbersException as err:
 
 For handling all possible exceptions thrown by this SDK use `SinchException` (superclass of all Sinch exceptions) form `sinch.core.exceptions`.
 
+
+## Custom HTTP client implementation
+
+By default, two HTTP implementations are provided:
+- Synchronous using `requests` HTTP library
+- Asynchronous using `aiohttp` HTTP library
+
+For creating custom HTTP client code, use either `Client` or `ClientAsync` client and inject your transport during initialisation:
+```python
+sinch_client = ClientAsync(
+    key_id="Spanish",
+    key_secret="Inquisition",
+    project_id="some_project",
+    transport=MyHTTPAsyncImplementation
+)
+```
+
+Custom client has to obey types and methods described by `HTTPTransport` abstract base class:
+```python
+class HTTPTransport(ABC):
+    @abstractmethod
+    def request(self, endpoint: HTTPEndpoint) -> HTTPResponse:
+        pass
+```
 ## License
 
 This project is licensed under the Apache License. See the [LICENSE](license.md) file for the license text.