Documentation: Recommend disabling clangd's IncludeCleaner feature

Author: https://github.com/ADKaster
Commit: https://github.com/SerenityOS/serenity/commit/713698d2ca
Pull-request: https://github.com/SerenityOS/serenity/pull/23078

Documentation/EmacsConfiguration.md

@@ -15,6 +15,10 @@ CompileFlags:
     - "-UNO_TLS"
     - "-I/path/to/serenity/Toolchain/Local/x86_64/x86_64-pc-serenity/include/c++/13.1.0"
     - "-I/path/to/serenity/Toolchain/Local/x86_64/x86_64-pc-serenity/include/c++/13.1.0/x86_64-pc-serenity"
+
+Diagnostics:
+  UnusedIncludes: None
+  MissingIncludes: None
 ```
 
 You will need to change `/path/to/serenity` and change `13.1.0` to

Documentation/HelixConfiguration.md

@@ -6,6 +6,10 @@ The following `.clangd` should be placed in the project root:
 CompileFlags:
   CompilationDatabase: Build/x86_64 # Or whatever architecture you're targeting, e.g. aarch64
   Add: [-D__serenity__]
+
+Diagnostics:
+  UnusedIncludes: None
+  MissingIncludes: None
 ```
 
 You also need to configure the clangd server to detect headers properly from the Serenity toolchain. To do this, create a `.helix/languages.toml` file in the project root:

Documentation/VSCodeConfiguration.md

@@ -25,8 +25,15 @@ Depending on which configuration you use most, set the CompilationDatabase confi
 CompileFlags:
   Add: [-D__serenity__]
   CompilationDatabase: Build/x86_64
+  
+Diagnostics:
+  UnusedIncludes: None
+  MissingIncludes: None
 ```
 
+The UnusedIncludes and MissingIncludes flags are used to disable the [Include Cleaner](https://clangd.llvm.org/design/include-cleaner) feature of newer clangd releases.
+It can be re-enabled if you don't mind the noisy inlay hints and problems in the problem view.
+
 Run ``./Meta/serenity.sh run`` at least once to generate the ``compile_commands.json`` file.
 
 In addition to the ``.clangd`` file, the ``settings.json`` file below has a required ``clangd.arguments`` entry for ``--query-driver`` that allows clangd to find the cross-compiler's built-in include paths.