Fix C++ configuration documentation (#19258)

- Update the binary JSON object
- Add .clangd configuration file summary


![image](https://github.com/user-attachments/assets/5c4cfd26-3cd8-4d12-96fc-483596c74287)

Release Notes:

- N/A

docs/src/languages/cpp.md

@@ -17,9 +17,38 @@ To use a binary in a custom location, add the following to your `settings.json`:
     "clangd": {
       "binary": {
         "path": "/path/to/clangd",
-        "args": []
+        "arguments": []
       }
     }
   }
 }
 ```
+
+If you want to disable Zed looking for a `clangd` binary, you can set `ignore_system-version` to `true`:
+
+```json
+{
+  "lsp": {
+    "clangd": {
+      "binary": {
+        "ignore_system_version": true
+      }
+    }
+  }
+}
+```
+
+## More server configuration
+
+In the root of your project, it is generally common to create a `.clangd` file to set extra configuration.
+
+```text
+CompileFlags:
+  Add:
+    - "--include-directory=/path/to/include"
+Diagnostics:
+  MissingIncludes: Strict
+  UnusedIncludes: Strict
+```
+
+For more advanced usage of clangd configuration file, take a look into their [official page](https://clangd.llvm.org/config.html).