docs: add example config for kate

Author: wkillerud

docs/src/language-server/existing-clients.md

@@ -3,3 +3,4 @@
 Editors with ready-configured clients, maintained by the community.
 
 - [Neovim](./neovim.md)
+- [Kate](./kate.md)

docs/src/language-server/kate.md

@@ -0,0 +1,29 @@
+# Kate
+
+The [Kate editor](https://kate-editor.org) has an LSP client where you can
+[configure your own servers](https://docs.kde.org/stable5/en/kate/kate/kate-application-plugin-lspclient.html).
+
+This is an example configuration. To apply it:
+
+- Open the Settings dialog
+- Go to the LSP Client category
+- Pick the User Server Settings tab
+
+```json
+{
+	"servers": {
+		"bash": {
+			"command": ["some-sass-language-server", "--stdio", "--debug"],
+			"url": "https://github.com/wkillerud/some-sass/packages/language-server",
+			"highlightingModeRegex": "^SCSS$"
+		}
+	}
+}
+```
+
+Note that this assumes that both `node` and `some-sass-language-server` is available on your `PATH`.
+
+For macOS users: GUI apps don't inherit the same `PATH` as your terminal.
+Configuring GUI apps to get the proper `PATH` varies with OS version. A consistent
+approach is launching the app from the terminal, for instance for Kate run
+`/Applications/kate.app/Contents/MacOS/kate`.