add providers to readme

Author: lalalune

README.md

@@ -148,11 +148,32 @@ const runtime = new BgentRuntime({
   evaluators: [fact],
 });
 
-// You can also register actions and evaluators after the runtime has been created
+// OR you can register actions and evaluators after the runtime has been created
 bgentRuntime.registerAction(wait);
 bgentRuntime.registerEvaluator(fact);
 ```
 
+## Custom Data Sources
+If you want to add custom data into the context that is sent to the LLM, you can create a `Provider` and add it to the runtime.
+
+```typescript
+import { type BgentRuntime, type Message, type Provider, type State } from "bgent";
+
+const time: Provider = {
+  // eslint-disable-next-line @typescript-eslint/no-unused-vars
+  get: async (_runtime: BgentRuntime, _message: Message, _state?: State) => {
+    const currentTime = new Date().toLocaleTimeString("en-US");
+    return "The current time is: " + currentTime;
+  },
+};
+
+const runtime = new BgentRuntime({
+  // ... other options
+  providers: [time],
+});
+```
+
+
 ## Handling User Input
 
 The BgentRuntime instance has a `handleMessage` method that can be used to handle user input. The method returns a promise that resolves to the agent's response.