feat: add readme for polywrap-wasm

Author: Niraj-Kamdar

packages/polywrap-wasm/README.md

@@ -1 +1,29 @@
-TODO
+# polywrap-wasm
+
+Python implementation of the Wasm wrapper runtime.
+
+## Usage
+
+### Invoke Wasm Wrapper
+
+```python
+from typing import cast
+from polywrap_manifest import AnyWrapManifest
+from polywrap_core import FileReader, Invoker
+from polywrap_wasm import WasmWrapper
+
+file_reader: FileReader = ... # any valid file_reader, pass NotImplemented for mocking
+wasm_module: bytes = bytes("<wrapper wasm module bytes read from file or http>")
+wrap_manifest: AnyWrapManifest = ...
+wrapper = WasmWrapper(file_reader, wasm_module, wrap_manifest)
+invoker: Invoker = ... # any valid invoker, mostly PolywrapClient
+
+message = "hey"
+args = {"arg": message}
+options: InvokeOptions[UriPackageOrWrapper] = InvokeOptions(
+  uri=Uri.from_str("fs/./build"), method="simpleMethod", args=args
+)
+result = await wrapper.invoke(options, invoker)
+assert result.encoded is True
+assert msgpack_decode(cast(bytes, result.result)) == message
+```