Update documentation

Author: mcbarton

Emscripten-build-instructions.md

@@ -33,20 +33,20 @@ source ./emsdk/emsdk_env.sh
 export SYSROOT_PATH=$PWD/emsdk/upstream/emscripten/cache/sysroot
 ```
 
-Now clone the 19.x release of the LLVM project repository and CppInterOp (the building of the emscripten version of llvm can be
+Now clone the 20.x release of the LLVM project repository and CppInterOp (the building of the emscripten version of llvm can be
 avoided by executing micromamba install llvm -c <https://repo.mamba.pm/emscripten-forge> and setting the LLVM_BUILD_DIR appropriately)
 
 
 ```bash
-git clone --depth=1 --branch release/19.x https://github.com/llvm/llvm-project.git
+git clone --depth=1 --branch release/20.x https://github.com/llvm/llvm-project.git
 git clone --depth=1 https://github.com/compiler-research/CppInterOp.git
 ```
 
 Now move into the cloned llvm-project folder and apply the required patches
 
 ```bash
 cd ./llvm-project/
-git apply -v ../CppInterOp/patches/llvm/emscripten-clang19-*.patch
+git apply -v ../CppInterOp/patches/llvm/emscripten-clang20-*.patch
 ```
 
 We are now in a position to build an emscripten build of llvm by executing the following

README.md

@@ -115,10 +115,10 @@ git clone --depth=1 https://github.com/compiler-research/cppyy-backend.git
 
 #### Setup Clang-REPL
 
-Clone the 19.x release of the LLVM project repository.
+Clone the 20.x release of the LLVM project repository.
 
 ```bash
-git clone --depth=1 --branch release/19.x https://github.com/llvm/llvm-project.git
+git clone --depth=1 --branch release/20.x https://github.com/llvm/llvm-project.git
 cd llvm-project
 ```
 

docs/DevelopersDocumentation.rst

@@ -34,11 +34,11 @@ library
  Setup Clang-REPL
 ******************
 
-Clone the 19.x release of the LLVM project repository.
+Clone the 20.x release of the LLVM project repository.
 
 .. code:: bash
 
-   git clone --depth=1 --branch release/19.x https://github.com/llvm/llvm-project.git
+   git clone --depth=1 --branch release/20.x https://github.com/llvm/llvm-project.git
    cd llvm-project
 
 For Clang 16 & 17, the following patches required for development work. To apply

docs/InstallationAndUsage.rst

@@ -34,11 +34,11 @@ library
  Setup Clang-REPL
 ******************
 
-Clone the 19.x release of the LLVM project repository.
+Clone the 20.x release of the LLVM project repository.
 
 .. code:: bash
 
-   git clone --depth=1 --branch release/19.x https://github.com/llvm/llvm-project.git
+   git clone --depth=1 --branch release/20.x https://github.com/llvm/llvm-project.git
    cd llvm-project
 
 For Clang 16 & 17, the following patches required for development work. To apply

docs/ReleaseNotes.md

@@ -25,7 +25,7 @@ infrastructure are described first.
 ## External Dependencies
 
 - CppInterOp now works with:
-  - llvm19
+  - llvm20
 
 ## Introspection