feat: Support project-level ls_specific_settings (#1192)

docs/02-usage/050_configuration.md

@@ -213,8 +213,10 @@ This ensures backward compatibility: existing projects that already have a `.ser
 Most users will not need to adjust these settings.
 :::
 
-Under the key `ls_specific_settings` in `serena_config.yml`, you can you pass per-language, 
-language server-specific configuration.
+Under the key `ls_specific_settings` in `serena_config.yml`, you can you pass global per-language, 
+language server-specific configuration. You can use the same key in the project configuration files (`project.yml`
+and `project.local.yml` ) to override or extend the global settings for a specific project.
+The settings are merged on top-level, meaning that project-level settings for a language will replace global settings for the same language.
 
 Structure:
 
@@ -230,6 +232,7 @@ Most settings are currently undocumented. Please refer to the
 implementation to determine supported settings.
 :::
 
+(override-ls-path)=
 #### Overriding the Language Server Path
 
 Some language servers, particularly those that use a single core path for the language server (e.g. the main executable),

docs/03-special-guides/cpp_setup.md

@@ -15,6 +15,8 @@ for cross-file reference finding, see below for details.
 Your project must have a `compile_commands.json` file at the repository root. 
 This file is essential for correct parsing and cross-file reference finding.
 
+You can use a specific clangd or ccls installation (e.g., a custom build or a version provided by your project),
+by specifying the path in your configuration, see [ls-specific-settings](ls-specific-settings) for details.
 
 ## compile_commands.json Requirements
 
@@ -27,7 +29,7 @@ For reliable cross-file reference finding with clangd, your `compile_commands.js
 
 ### With clangd
 
-Serena automatically downloads and manages clangd. Since clangd does not properly work with relative paths in `compile_commands.json`,
+By default, Serena automatically downloads and manages clangd. Since clangd does not properly work with relative paths in `compile_commands.json`,
 Serena will detect them and transform them into absolute paths automatically (writing a new `compile_commands.json` file), if needed.
 
 #### Customizing the Compilation Database Location