update readme

Author: fumito-ito

README.md

@@ -1,2 +1,88 @@
 # FunctionCalling-AIProxySwift
-Easy to use your Swift native functions for function calling with AIProxySwift.
+
+This library simplifies the integration of the [FunctionCalling](https://github.com/fumito-ito/FunctionCalling) macro into [AIProxySwift](https://github.com/lzell/AIProxySwift). By using this library, you can directly generate `Tool` objects from Swift native functions, which can then be specified as FunctionCalling when invoking AIProxy.
+
+## Usage
+
+```swift
+
+import FunctionCalling
+import FunctionCalling_AIProxySwift
+import AIProxy
+
+// MARK: Declare the container and functions for the tools to be called from FunctionCalling.
+
+@FunctionCalling(service: .chatGPT)
+struct MyFunctionTools {
+    @CallableFunction
+    /// Get the current stock price for a given ticker symbol
+    ///
+    /// - Parameter: The stock ticker symbol, e.g. GOOG for Google Inc.
+    func getStockPrice(ticker: String) async throws -> String {
+        // code to return stock price of passed ticker
+    }
+}
+
+// MARK: You can directly pass the tools generated from objects to the model in AIProxy.
+
+let openAIService = AIProxy.openAIService(
+    partialKey: "partial-key-from-your-developer-dashboard",
+    serviceURL: "service-url-from-your-developer-dashboard"
+)
+
+do {
+    let requestBody = OpenAIChatCompletionRequestBody(
+        model: "gpt-4o-2024-08-06",
+        messages: [
+            .user(content: .text("How cold is it today in SF?"))
+        ],
+        tools: MyFunctionTools().toOpenAITools()
+    )
+
+    let response = try await openAIService.chatCompletionRequest(body: requestBody)
+    if let toolCall = response.choices.first?.message.toolCalls?.first {
+        let functionName = toolCall.function.name
+        let arguments = toolCall.function.arguments ?? [:]
+        print("ChatGPT wants us to call function \(functionName) with arguments: \(arguments)")
+    } else {
+        print("Could not get function arguments")
+    }
+
+} catch AIProxyError.unsuccessfulRequest(let statusCode, let responseBody) {
+    print("Received \(statusCode) status code with response body: \(responseBody)")
+} catch {
+    print("Could not make an OpenAI structured output tool call: \(error.localizedDescription)")
+}
+```
+
+## Installation
+
+### Swift Package Manager
+
+```
+let package = Package(
+    name: "MyPackage",
+    products: [...],
+    targets: [
+        .target(
+            "YouAppModule",
+            dependencies: [
+                .product(name: "FunctionCalling-AIProxySwift", package: "FunctionCalling-AIProxySwift")
+            ]
+        )
+    ],
+    dependencies: [
+        .package(url: "https://github.com/FunctionCalling/FunctionCalling-AIProxySwift", from: "0.1.0")
+    ]
+)
+```
+
+## Contributing
+
+Pull requests are welcome. For major changes, please open an issue first to discuss what you would like to change.
+
+Please make sure to update tests as appropriate.
+
+## License
+
+Apache v2 License