docs: Fix typo in configuring-zed.md (#18178)

Fix typo in `configuring-zed.md`

Release Notes:

- N/A

docs/src/configuring-zed.md

@@ -313,10 +313,10 @@ List of `string` values
 "cursor_shape": "block"
 ```
 
-3. An underline that runs along the following character:
+3. An underscore that runs along the following character:
 
 ```json
-"cursor_shape": "underline"
+"cursor_shape": "underscore"
 ```
 
 4. An box drawn around the following character: