Add CONTRIBUTING.md (#13)

Author: savq

CONTRIBUTING.md

@@ -0,0 +1,30 @@
+# Contributing
+
+**Make sure to read the following documentation:**
+
+- [Developing Extensions](https://zed.dev/docs/extensions/developing-extensions)
+- [Language Extensions](https://zed.dev/docs/extensions/languages)
+
+
+## Filing issues
+
+Before reporting an issue,
+check [existing issues](https://github.com/JuliaEditorSupport/zed-julia/issues?q=is%3Aissue)
+(including closed issues).
+
+The Julia Zed extension is mostly glue code that defines how Zed should use
+tree-sitter and the language server protocol with Julia. Please report issues
+in the appropriate issue tracker.
+
+### tree-sitter integration
+
+If Zed is not highlighting something properly,
+check the queries defined in: [`./languages/julia/*.scm`](./languages/julia/).
+
+If the issue does not seem to be related to the way queries are defined,
+check the [tree-sitter-julia issue tracker](https://github.com/tree-sitter/tree-sitter-julia/issues).
+
+### Language server integration
+
+If you find an issue with the language server,
+check the [LanguageServer.jl issue tracker](https://github.com/julia-vscode/LanguageServer.jl/issues).