docs: Fix casing of "Tree-sitter" (#25427)

This PR fixes the casing of "Tree-sitter" in the docs.

It is "Tree-sitter", not "Tree Sitter" or "Tree-Sitter".

Release Notes:

- N/A

docs/src/languages/csharp.md

@@ -4,7 +4,7 @@ Note language name is "CSharp" for settings not "C#'
 
 C# support is available through the [C# extension](https://github.com/zed-industries/zed/tree/main/extensions/csharp).
 
-- Tree Sitter: [tree-sitter/tree-sitter-c-sharp](https://github.com/tree-sitter/tree-sitter-c-sharp)
+- Tree-sitter: [tree-sitter/tree-sitter-c-sharp](https://github.com/tree-sitter/tree-sitter-c-sharp)
 - Language Server: [OmniSharp/omnisharp-roslyn](https://github.com/OmniSharp/omnisharp-roslyn)
 
 ## Configuration