Update README.md with architecture details and add allocator diagram

Author: oligamiq

threads/README.md

@@ -26,3 +26,18 @@ $ git submodule update --init
 $ cd examples && npm install && npm run dev
 ```
 And visit http://localhost
+
+# Architecture
+In the thread that maintains the file system for `@bjorn3/browser_wasi_shim`, file access is awaited asynchronously, while in the thread executing the WASM, file access is performed synchronously.
+
+Since the functions called within the WASM are invoked synchronously, it is not possible to properly create web workers. Therefore, it is necessary to first create a dedicated thread for generating web workers.
+
+Please refer to the diagram below for more details.
+
+<!-- @/architecture/slide1.svg -->
+![slide1](./architecture/slide1.svg)
+
+Additionally, since data of unknown size is being exchanged, an allocator is essential. A simple allocator is implemented on the assumption that the allocated memory will be released promptly.
+
+<!-- @/architecture/slide2.svg -->
+![slide2](./architecture/slide2.svg)