Remove windows aarch stencil and update README

Author: savannahostrowski

Tools/jit/README.md

@@ -1,17 +1,31 @@
 The JIT Compiler
 ================
 
-This version of CPython can be built with an experimental just-in-time compiler[^pep-744]. While most everything you already know about building and using CPython is unchanged, you will probably need to install a compatible version of LLVM first.
+This version of CPython can be built with an experimental just-in-time compiler[^pep-744].
 
-## Installing LLVM
+## Building CPython with the JIT enabled
+
+For `PCbuild`-based builds, pass the new `--experimental-jit` option to `build.bat`.
+
+For all other builds, pass the new `--enable-experimental-jit` option to `configure`.
+
+Otherwise, just configure and build as you normally would. Cross-compiling "just works", since the JIT is built for the host platform. 
+
+The JIT can also be enabled or disabled using the `PYTHON_JIT` environment variable, even on builds where it is enabled or disabled by default. More details about configuring CPython with the JIT and optional values for `--enable-experimental-jit` can be found [here](https://docs.python.org/dev/whatsnew/3.13.html#experimental-jit-compiler).
+
+## Contributing to the JIT
+
+While LLVM is not a build-time dependency as stencils as hosted in `Tools/jit/stencils`, you may still want to install LLVM to simplify your local development process (e.g. not have to wait for a CI run to regenerate the stencil for your platform).
+
+###  Installing LLVM
 
 The JIT compiler does not require end users to install any third-party dependencies, but part of it must be *built* using LLVM[^why-llvm]. You are *not* required to build the rest of CPython using LLVM, or even the same version of LLVM (in fact, this is uncommon).
 
 LLVM version 19 is required. Both `clang` and `llvm-readobj` need to be installed and discoverable (version suffixes, like `clang-19`, are okay). It's highly recommended that you also have `llvm-objdump` available, since this allows the build script to dump human-readable assembly for the generated code.
 
 It's easy to install all of the required tools:
 
-### Linux
+#### Linux
 
 Install LLVM 19 on Ubuntu/Debian:
 
@@ -27,7 +41,7 @@ Install LLVM 19 on Fedora Linux 40 or newer:
 sudo dnf install 'clang(major) = 19' 'llvm(major) = 19'
 ```
 
-### macOS
+#### macOS
 
 Install LLVM 19 with [Homebrew](https://brew.sh):
 
@@ -37,7 +51,7 @@ brew install llvm@19
 
 Homebrew won't add any of the tools to your `$PATH`. That's okay; the build script knows how to find them.
 
-### Windows
+#### Windows
 
 Install LLVM 19 [by searching for it on LLVM's GitHub releases page](https://github.com/llvm/llvm-project/releases?q=19), clicking on "Assets", downloading the appropriate Windows installer for your platform (likely the file ending with `-win64.exe`), and running it. **When installing, be sure to select the option labeled "Add LLVM to the system PATH".**
 
@@ -47,17 +61,6 @@ Alternatively, you can use [chocolatey](https://chocolatey.org):
 choco install llvm --version=19.1.0
 ```
 
-
-## Building
-
-For `PCbuild`-based builds, pass the new `--experimental-jit` option to `build.bat`.
-
-For all other builds, pass the new `--enable-experimental-jit` option to `configure`.
-
-Otherwise, just configure and build as you normally would. Cross-compiling "just works", since the JIT is built for the host platform. 
-
-The JIT can also be enabled or disabled using the `PYTHON_JIT` environment variable, even on builds where it is enabled or disabled by default. More details about configuring CPython with the JIT and optional values for `--enable-experimental-jit` can be found [here](https://docs.python.org/dev/whatsnew/3.13.html#experimental-jit-compiler).
-
 [^pep-744]: [PEP 744](https://peps.python.org/pep-0744/)
 
 [^why-llvm]: Clang is specifically needed because it's the only C compiler with support for guaranteed tail calls (`musttail`), which are required by CPython's continuation-passing-style approach to JIT compilation. Since LLVM also includes other functionalities we need (namely, object file parsing and disassembly), it's convenient to only support one toolchain at this time.