Add installation instructions to LSP plugin READMEs

Each README now includes:
- Supported file extensions
- Installation commands for different platforms/package managers
- Links to project websites and documentation

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

plugins/clangd-lsp/README.md

@@ -1,8 +1,36 @@
 # clangd-lsp
 
-This plugin provides LSP (Language Server Protocol) integration for Claude Code.
+C/C++ language server (clangd) for Claude Code, providing code intelligence, diagnostics, and formatting.
 
-## Requirements
+## Supported Extensions
+`.c`, `.h`, `.cpp`, `.cc`, `.cxx`, `.hpp`, `.hxx`, `.C`, `.H`
 
-The corresponding language server must be installed on your system. The plugin will be recommended when you edit files with the supported extensions and have the language server binary available.
+## Installation
 
+### Via Homebrew (macOS)
+```bash
+brew install llvm
+# Add to PATH: export PATH="/opt/homebrew/opt/llvm/bin:$PATH"
+```
+
+### Via package manager (Linux)
+```bash
+# Ubuntu/Debian
+sudo apt install clangd
+
+# Fedora
+sudo dnf install clang-tools-extra
+
+# Arch Linux
+sudo pacman -S clang
+```
+
+### Windows
+Download from [LLVM releases](https://github.com/llvm/llvm-project/releases) or install via:
+```bash
+winget install LLVM.LLVM
+```
+
+## More Information
+- [clangd Website](https://clangd.llvm.org/)
+- [Getting Started Guide](https://clangd.llvm.org/installation)