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/csharp-lsp/README.md

@@ -1,8 +1,25 @@
 # csharp-lsp
 
-This plugin provides LSP (Language Server Protocol) integration for Claude Code.
+C# language server for Claude Code, providing code intelligence and diagnostics.
+
+## Supported Extensions
+`.cs`
+
+## Installation
+
+### Via .NET tool (recommended)
+```bash
+dotnet tool install --global csharp-ls
+```
+
+### Via Homebrew (macOS)
+```bash
+brew install csharp-ls
+```
 
 ## Requirements
+- .NET SDK 6.0 or later
 
-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.
-
+## More Information
+- [csharp-ls GitHub](https://github.com/razzmatazz/csharp-language-server)
+- [.NET SDK Download](https://dotnet.microsoft.com/download)