docs: add more schedule sources

Author: danfimov

docs/available-components/schedule-sources.md

@@ -5,9 +5,12 @@ order: 4
 # Available schedule sources
 
 These objects are used to fetch current schedule for tasks.
-Currently we have only one schedule source.
 
-## RedisScheduleSource
+## Official schedule sources
+
+These schedule sources are not part of the core Taskiq library. But they are maintained by Taskiq developers. You can install them as a separate package.
+
+### RedisScheduleSource
 
 This source is capable of adding new schedules in runtime. It uses Redis as a storage for schedules.
 To use this source you need to install `taskiq-redis` package.
@@ -24,7 +27,7 @@ scheduler = TaskiqScheduler(broker, sources=[redis_source])
 For more information on how to use dynamic schedule sources read [Dynamic scheduling section](../guide/scheduling-tasks.md#dynamic-scheduling).
 
 
-## LabelScheduleSource
+### LabelScheduleSource
 
 This source parses labels of tasks, and if it finds a `schedule` label, it considers this task as scheduled.
 
@@ -76,3 +79,43 @@ In order to resolve all labels correctly, don't forget to import
 all task modules using CLI interface.
 
 :::
+
+### NATS schedule source
+
+This source is capable of adding new schedules in runtime. It uses NATS as a storage for schedules.
+To use this source you need to install `taskiq-nats` package.
+
+```python
+from taskiq_nats import NATSKeyValueScheduleSource
+from taskiq.scheduler import TaskiqScheduler
+
+
+broker = ...
+
+scheduler = TaskiqScheduler(
+    broker=broker,
+    sources=[NATSKeyValueScheduleSource(broker)],
+)
+```
+
+This schedule source doesn't use `schedule` label on tasks. To add new schedules, you need to call `add_schedule` method on the source.
+
+## Third-party schedule sources
+
+These schedule sources are not part of the core Taskiq library. They are maintained by other open‑source contributors. You can install them as a separate packages.
+
+### PostgreSQL schedule source
+
+Project link: [taskiq-postgres](https://github.com/danfimov/taskiq-postgres)
+
+```bash
+pip install taskiq-postgres
+```
+
+### YDB schedule source
+
+Project link: [taskiq-ydb](https://github.com/danfimov/taskiq-ydb)
+
+```bash
+pip install taskiq-ydb
+```