Update game directory description (we do have audio) (#1460)

* Update `game` directory description(we have audio)

* typing is hard

README.md

@@ -298,9 +298,10 @@ The third is the game source code, written in OpenGOAL. This is located in `goal
 The final component is the "runtime", located in `game`. This is the part of the game that's written in C++. In the port, that includes:
 - The "C Kernel", which contains the GOAL linker and some low-level GOAL language features. GOAL has a completely custom dynamically linked object file format so in order to load the first GOAL code, you need a linker written in C++. Some low-level functions for memory allocation, communicating with the I/O Processor, symbol table, strings, and the type system are also implemented in C, as these are required for the linker. It also listens for incoming messages from the compiler and passes them to the running game. This also initializes the game, by initializing the PS2 hardware, allocating the GOAL heaps, loading the GOAL kernel off of the DVD, and executing the kernel dispatcher function. This is in the `game/kernel` folder. This should be as close as possible to the game, and all differences should be noted with a comment.
 - Implementation of Sony's standard library. GOAL code can call C library functions, and Naughty Dog used some Sony library functions to access files, memory cards, controllers, and communicate with the separate I/O Processor. The library functions are in `game/sce`. Implementations of library features specific to the PC port are located in `game/system`.
-- The I/O Processor driver, Overlord. The PS2 had a separate CPU called the I/O Processor (IOP) that was directly connected to the DVD drive hardware and the sound hardware. Naughty Dog created a custom driver for the IOP that handled streaming data off of the DVD. It is much more complicated than I first expected. It's located in `game/overlord`. Like the C kernel, we try to keep this as close as possible to the actual game.
-- Sound Code. Naughty Dog used a third party library for sound. We have not started on this yet.
-- PC specific graphics stuff. We have a functional OpenGL renderer and context that can create a game window and display graphics on it. The specific renderers used by the game however are mostly unimplemented. We have a debug, sprite and tfrag renderers, which is enough to render most of the game world, on-screen text and sprites like the progress menu. This is located in `game/graphics`. Many liberties will be taken to make this work, but the end result should closely match the actual game.
+- The I/O Processor driver, OVERLORD. The PS2 had a separate CPU called the I/O Processor (IOP) that was directly connected to the DVD drive hardware and the sound hardware. Naughty Dog created a custom driver for the IOP that handled streaming data off of the DVD. It is much more complicated than I first expected. It's located in `game/overlord`. Like the C kernel, we try to keep this as close as possible to the actual game.
+- Sound code. Naughty Dog used a third party library for sound called `989SND`. Code for the library and an interface for it is located in `game/sound`.
+- PC specific graphics code. We have a functional OpenGL renderer and context that can create a game window and display graphics on it. The specific renderers used by the game however are mostly implemented. Aside from post-processing effects, everything in the game is rendered. This is located in `game/graphics`. While many liberties will be taken to make this work, the end result should very closely match the actual game.
+- Extra assets used by the port in some fashion, located in `game/assets`. These include extra text files, icons, etc.
 
 ## Directory Layout