CLion IDE added to the "Configuring an IDE" page. (#3021)

* CLion IDE added to the "Configuring an IDE" page.

* Language and markup fixes

Co-authored-by: Rémi Verschelde <rverschelde@gmail.com>

development/cpp/configuring_an_ide.rst

@@ -16,6 +16,7 @@ Development Environment), here are setup instructions for some popular ones:
 - :ref:`Visual Studio <doc_compiling_for_windows_install_vs>` (Windows)
 - :ref:`Visual Studio Code<doc_configuring_an_ide_vscode>` (all desktop platforms)
 - :ref:`Android Studio<doc_configuring_an_ide_android_studio>` (all desktop platforms)
+- :ref:`CLion<doc_configuring_an_ide_clion>` (all desktop platforms)
 
 It is possible to use other IDEs, but their setup is not documented yet.
 
@@ -316,3 +317,26 @@ Project setup
 - Navigate to ``<godot root directory>/platform/android/java`` and select the ``settings.gradle`` gradle file.
 - Android Studio will import and index the project.
 - To build the project, follow the :ref:`compiling instructions <toc-devel-compiling>`.
+
+.. _doc_configuring_an_ide_clion:
+
+CLion
+-----
+
+`CLion <https://www.jetbrains.com/clion/>`_ is a commercial IDE for C++. It requires a ``CMakeLists.txt`` file as a project file, which is problematic for Godot which uses the SCons buildsystem and not CMake. However, there is a ``CMakeLists.txt`` configuration for :ref:`Android Studio <doc_configuring_an_ide_android_studio>` which can also be used by CLion.
+
+- Choose *File* -> *Open*.
+
+- Navigation to your Godot Git clone, and select the folder ``platform/android/java/lib`` (the ``CMakeLists.txt`` file is located there). Select the folder, not the ``CMakeLists.txt file``. Then click *Ok*.
+
+.. image:: img/clion_1_open.png
+
+- If this popup window appears, select *This window* to open the project.
+
+.. image:: img/clion_2_this_window.png
+
+- Choose *Tools* -> *CMake* -> *Change Project Root* and select the root Godot folder.
+
+.. image:: img/clion_3_change_project_root.png
+
+- You should be now be able to see all the project files. Autocomplete should work, when the project finish indexing.