Added docs

Author: chandr-andr

README.md

@@ -1 +1,64 @@
 # TaskIQ - PSQLPy
+
+TaskIQ-PSQLPy is a plugin for taskiq that adds a new result backend based on PostgreSQL and [PSQLPy](https://github.com/qaspen-python/psqlpy).
+
+## Installation
+To use this project you must have installed core taskiq library:
+```bash
+pip install taskiq
+```
+
+This project can be installed using pip:
+```bash
+pip install taskiq-psqlpy
+```
+
+Or using poetry:
+```
+poetry add taskiq-psqlpy
+```
+
+## Usage
+Let's see the example with the redis broker and PostgreSQL PSQLPy result backend:
+```python
+# broker.py
+import asyncio
+
+from taskiq_redis import ListQueueBroker
+from taskiq_psqlpy import PSQLPyResultBackend
+
+psqlpy_result_backend = PSQLPyResultBackend(
+    dsn="postgres://postgres:postgres@localhost:5432/postgres",
+)
+
+# Or you can use PubSubBroker if you need broadcasting
+broker = ListQueueBroker(
+    url="redis://localhost:6379",
+    result_backend=psqlpy_result_backend,
+)
+
+
+@broker.task
+async def best_task_ever() -> None:
+    """Solve all problems in the world."""
+    await asyncio.sleep(5.5)
+    print("All problems are solved!")
+
+
+async def main():
+    await broker.startup()
+    task = await best_task_ever.kiq()
+    print(await task.wait_result())
+    await broker.shutdown()
+
+
+if __name__ == "__main__":
+    asyncio.run(main())
+```
+
+## PSQLPyResultBackend configuration
+- `dsn`: connection string to PostgreSQL.
+- `keep_results`: flag to not remove results from Redis after reading.
+- `table_name`: name of the table in PostgreSQL to store TaskIQ results.
+- `field_for_task_id`: type of a field for `task_id`, you may need it if you want to have length of task_id more than 255 symbols.
+- `**connect_kwargs`: additional connection parameters, you can read more about it in [PSQLPy](https://github.com/qaspen-python/psqlpy) repository.

taskiq_psqlpy/__init__.py

@@ -0,0 +1,5 @@
+from taskiq_psqlpy.result_backend import PSQLPyResultBackend
+
+__all__ = [
+    "PSQLPyResultBackend",
+]

taskiq_psqlpy/result_backend.py

@@ -1,5 +1,5 @@
 import pickle
-from typing import Any, Final, Literal, TypeVar, cast
+from typing import Any, Final, Literal, Optional, TypeVar, cast
 
 from psqlpy import PSQLPool
 from psqlpy.exceptions import RustPSQLDriverPyBaseError
@@ -23,7 +23,7 @@ class PSQLPyResultBackend(AsyncResultBackend[_ReturnType]):
 
     def __init__(
         self,
-        dsn: str = "postgres://postgres:postgres@localhost:5432/postgres",
+        dsn: Optional[str] = "postgres://postgres:postgres@localhost:5432/postgres",
         keep_results: bool = True,
         table_name: str = "taskiq_results",
         field_for_task_id: Literal["VarChar", "Text"] = "VarChar",