Update docs with detailings in usage of CppInterOp

docs/UsingCppInterOp.rst

@@ -4,6 +4,9 @@ Using CppInterop
 C++ Language Interoperability Layer
 ===================================
 
+Loading Dynamic shared library
+==============================
+
 The CppInterop comes with using it is a dynamic shared library, 
 **libclangCppInterOp.so** which resides in the CppInterOp/build/lib/.
 
@@ -20,6 +23,31 @@ classes and members that are being used. The interoperability layer helps us
 with the instantiation of templates, diagnostic interaction, creation of 
 objects, and many more things.
 
+Using LLVM as external library
+==============================
+
+In CppInterOp, we are leveraging Clang as a library for interoperability purposes.
+To use Clang, we need to pass the Clang configuration to the CMake build system,
+so that the build system recognises the configuration and enables usage of Clang
+and LLVM.
+We can consider clang-repl as a state manager, where CppInterOp allows you to
+query the state from the state manager. Thereafter, Cppyy uses this to create
+Python objects for C++.
+
+.. code-block:: bash
+
+   # Apply the patches for development
+   compgen -G "../patches/llvm/clang16-*.patch" > /dev/null
+   && find ../patches/llvm/clang16-*.patch -printf "%f\n"
+   && git apply ../patches/llvm/clang16-*.patch
+
+.. code-block:: bash
+
+    # Use the versions of llvm with above patches applied
+    -DClang_DIR=/usr/lib/llvm-16/build/lib/cmake/clang\
+    -DLLVM_DIR=/usr/lib/llvm-16/build/lib/cmake/llvm
+
+
 This section briefly describes all the key **features** offered by 
 CppInterop. If you are just getting started with CppInterop, then this is the 
 best place to start.