Add docs

Signed-off-by: Danila Fedorin <daniel.fedorin@hpe.com>

Author: DanilaFe

doc/rst/usingchapel/compiling.rst

@@ -241,3 +241,16 @@ code:
    add_executable(myChapelProgram main.chpl)
    target_link_options(main PRIVATE -I${CMAKE_SOURCE_DIR}/include)
    target_link_libraries(myChapelProgram PRIVATE myCCode)
+
+To enable use of CMake-based projects with the :ref:`language server <readme-chpl-language-server>`,
+the CMake integration provides a special variable ``CMAKE_EXPORT_CHPL_COMMANDS``.
+When set to ``ON``, CMake will generate a file named ``.cls_commands.json`` in
+the build directory. This file can be read by the language server to understand
+the module structure of the project. For example:
+
+.. code-block:: sh
+
+   mkdir build && cd build
+   cmake .. -CMAKE_EXPORT_CHPL_COMMANDS=ON
+   cmake --build .
+   cd .. && ln -s build/.cls_commands.json .cls_commands.json

util/cmake/README.md

@@ -15,3 +15,13 @@ project(hello LANGUAGES CHPL)
 
 add_executable(hello hello.chpl)
 ```
+
+## Language Server Integration
+
+To enable Chapel Language Server integration, set `CMAKE_EXPORT_CHPL_COMMANDS` to `ON`:
+
+```cmake
+set(CMAKE_EXPORT_CHPL_COMMANDS ON)
+```
+
+This will generate a `.cls-commands.json` file in your build directory that the Chapel Language Server can use to understand your project's module paths and source files.