docs: Add initial language settings documentation (#6957)

This pull request implements the following documentation changes:

- [x] Copy existing language settings docs from old docs repo
- [x] Add new pages for Zig, Haskell, Gleam, Deno and PureScript
- [x] Add `rust-analyzer` target directory section to Rust language page

Release Notes:

- Added initial language settings documentation
([#4264](https://github.com/zed-industries/zed/issues/4264)).

docs/src/languages/ruby.md

@@ -0,0 +1,39 @@
+# Ruby
+
+- Tree Sitter: [tree-sitter-ruby](https://github.com/tree-sitter/tree-sitter-ruby)
+- Language Server: [solargraph](https://github.com/castwide/solargraph)
+
+### Setup
+
+Zed currently doesn't install Solargraph automatically. To use Solargraph, you need to install the gem. Zed just looks for an executable called `solargraph` on your `PATH`.
+
+You can install the gem manually with the following command:
+
+```shell
+gem install solargraph
+```
+
+Alternatively, if your project uses Bundler, you can add the Solargraph gem to your `Gemfile`:
+
+```ruby
+gem 'solargraph', group: :development
+```
+
+Solargraph has formatting and diagnostics disabled by default. We can tell Zed to enable them by adding the following to your `settings.json`:
+
+```json
+{
+   "lsp": {
+      "solargraph": {
+         "initialization_options": {
+            "diagnostics": true,
+            "formatting": true
+         }
+      }
+   }
+}
+```
+
+### Configuration
+
+Solargraph reads its configuration from a file called `.solargraph.yml` in the root of your project. For more information about this file, see the [Solargraph configuration documentation](https://solargraph.org/guides/configuration).