Update README.md

README.md

@@ -5,13 +5,37 @@ Let's try make a Wii U Toolchain / SDK for creating rpx/rpl.
 
 Licensed under the terms of the GNU General Public License, version 2 or later (GPLv2+).
 
-## Requirements
+## Usage
+See [samples](samples) for examples of how to use wut.
+
+The [share/wut.cmake](share/wut.cmake) file provides several helpers for your build:
+- `wut_create_rpx(target.rpx executable)` - Will create an .rpx file from your CMake target generated by `add_executable`
+- `wut_enable_newlib(target)` - Links against the wut implementation of newlib, this is useful for using any function from the C standard library
+- `wut_enable_stdcpp(target)` - Links against the wut implementation of stdcpp, this is useful for using any function from the C++ standard library. This will call wut_enable_newlib if you have not already done so.
+- `wut_default_malloc(target)` - By default newlib will allocate 90% of the default heap for use with sbrk & malloc, if this is unacceptable to you then you should use this as it replaces the newlib malloc functions which ones which redirect to the CafeOS default heap functions such as MEMAllocFromDefaultHeap.
+- `wut_enable_devoptab_sd(target)` - This links in wutdevoptab_sd which is useful for using the libc file functions with paths such as `fopen("sd:/file.txt", "r")` to read files from the sd card
+
+A minimal CMakeLists.txt file for a C++ project might look like:
+```
+cmake_minimum_required(VERSION 3.2)
+project(helloworld_cpp CXX)
+include("${WUT_ROOT}/share/wut.cmake" REQUIRED)
+
+add_executable(helloworld_cpp
+   main.cpp)
+
+wut_enable_stdcpp(helloworld_cpp)
+wut_create_rpx(helloworld_cpp.rpx helloworld_cpp)
+```
+
+## Building
+Requires:
 - A modern compiler with C++14/17 support
 - CMake
 - zlib
 - [devkitPPC r31+](https://devkitpro.org/wiki/Getting_Started)
 
-## Windows
+### Building on Windows
 Use [WSL](https://docs.microsoft.com/en-us/windows/wsl/install-win10) and then follow the Linux instructions.
 
 For example, if you installed Ubuntu then you might setup your environment like:
@@ -23,7 +47,7 @@ sudo dpkg -i devkitpro-pacman.deb
 sudo dkp-pacman -S devkitPPC wiiload
 ```
 
-## Linux / MacOS
+### Building on Linux / MacOS
 ```
 export DEVKITPPC=/opt/devkitpro/devkitPPC
 git clone --recursive https://github.com/decaf-emu/wut.git