docs: add usage documentation

README.md

@@ -1,3 +1,52 @@
 # Synctactic
 
 Lightweight one-way background syncing library.
+
+## Installation
+
+```bash
+npm install synctactic
+```
+
+## Features
+
+- Sync data from any store to any persistent storage (database, local storage, etc.)
+- Sync only when data changes
+- Force manual sync
+- Disable previous syncs when a new one is triggered
+- Notify when closing the tab and there is a pending sync in the background
+
+## Usage
+
+```typescript
+import { sync } from 'synctactic';
+import { store } from './store';
+import { sendData } from './api';
+
+const { forceSync, unSync } = sync({
+  // Subscribe to store changes.
+  subscribe: store.subscribe,
+
+  // Sync on store change. Passing an `abortSignal` allows to cancel the sync.
+  syncFn: async (abortSignal) => {
+    await sendData(store.getState(), abortSignal);
+  },
+
+  options: {
+    // Debounce time between syncs. Optional. Defaults to `0`.
+    wait: 1000,
+
+    // Notify for pending sync on tab close. Optional. Defaults to `false`.
+    notifyOnLeave: true,
+  },
+});
+
+// Triggers a sync.
+store.dispatch({ type: 'change' });
+
+// Force a sync manually.
+forceSync();
+
+// Stop syncing and cleanup.
+unSync();
+```