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/javascript.md

@@ -2,7 +2,7 @@
 
 JavaScript support is available natively in Zed.
 
-- Tree Sitter: [tree-sitter/tree-sitter-javascript](https://github.com/tree-sitter/tree-sitter-javascript)
+- Tree-sitter: [tree-sitter/tree-sitter-javascript](https://github.com/tree-sitter/tree-sitter-javascript)
 - Language Server: [typescript-language-server/typescript-language-server](https://github.com/typescript-language-server/typescript-language-server)
 
 ## Code formatting