DOC: Update instructions to build NumPy on WoA

Author: MugundanMCW

doc/source/building/index.rst

@@ -226,21 +226,21 @@ your system.
     In Windows on ARM64, the set of a compiler options that are available for
     building NumPy are limited. Compilers such as GCC and GFortran are not yet
     supported for Windows on ARM64. Currently, the NumPy build for Windows on ARM64
-    is supported with MSVC toolchain only. The use of a Fortran compiler is more
-    tricky than on other platforms, because MSVC does not support Fortran, and
+    is supported with MSVC and LLVM toolchains. The use of a Fortran compiler is
+    more tricky than on other platforms, because MSVC does not support Fortran, and
     gfortran and MSVC can't be used together. If you don't need to run the ``f2py``
     tests, simply using MSVC is easiest. Otherwise, you will need the following
     set of compilers:
 
-    1. MSVC + Flang-new (``flang-new``)
+    1. MSVC + flang (``cl``, ``flang``)
+    2. LLVM + flang (``clang-cl``, ``flang``)
 
     First, install Microsoft Visual Studio - the 2022 Community Edition will
-    work(see the `Visual Studio download site <https://visualstudio.microsoft.com/downloads/>`__).
-    In order to ensure you have the Windows Universal C Runtime (the other components
-    of Visual Studio can be deselected if desired, to save disk space). The
-    recommended version of the UCRT is >= 10.0.22621.0.
+    work (see the `Visual Studio download site <https://visualstudio.microsoft.com/downloads/>`__).
+    Ensure that you have installed necessary Visual Studio components for building NumPy 
+    on WoA from `here <https://gist.github.com/Mugundanmcw/c3bb93018d5da9311fb2b222f205ba19>`__.
 
-    To use flang-new fortran compiler for Windows on ARM64, install Latest LLVM
+    To use the flang compiler for Windows on ARM64, install Latest LLVM
     toolchain for WoA from `here <https://github.com/llvm/llvm-project/releases>`__.
 
     .. tab-set::
@@ -257,6 +257,14 @@ your system.
         For detailed guidance, see `Use the Microsoft C++ toolset from the command line
         <https://learn.microsoft.com/en-us/cpp/build/building-on-the-command-line?view=msvc-170>`__.
 
+      .. tab-item:: LLVM
+
+        Similar to MSVC, LLVM does not put the compilers on the system path.
+        To set system path for LLVM compilers, users may need to use ``set``
+        command to put compilers on the system path. To check compiler's path
+        for LLVM's clang-cl, try invoking LLVM's clang-cl compiler in the shell you use
+        (``clang-cl --version``).
+
     .. note::
 
         Compilers should be on the system path (i.e., the ``PATH`` environment
@@ -265,7 +273,7 @@ your system.
         will be found automatically if and only if there are no other compilers
         on the ``PATH``. You can use any shell (e.g., Powershell, ``cmd`` or
         Git Bash) to invoke a build. To check that this is the case, try
-        invoking a Fortran compiler in the shell you use (e.g., ``flang-new
+        invoking a Fortran compiler in the shell you use (e.g., ``flang
         --version``).
 
     .. warning::
@@ -428,7 +436,7 @@ virtual environments:
           Building NumPy with BLAS and LAPACK functions requires OpenBLAS
           library at Runtime. In Windows on ARM64, this can be done by setting
           up pkg-config for OpenBLAS dependency. The build steps for OpenBLAS
-          for Windows on ARM64 can be found `here <https://github.com/OpenMathLib/OpenBLAS/blob/develop/docs/install.md#windows-on-arm>`__.
+          for Windows on ARM64 can be found `here <http://www.openmathlib.org/OpenBLAS/docs/install/#windows-on-arm>`__.
 
 
     Then install the Python-level dependencies from PyPI with::