docs: Add missing quote in JSON snippet (#30303)

gak created 

Release Notes:

- N/A

Change summary

docs/src/languages/rust.md | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

Detailed changes

docs/src/languages/rust.md 🔗 

@@ -127,7 +127,7 @@ This is enabled by default and can be configured as
 ```json
 "lsp": {
   "rust-analyzer": {
-    enable_lsp_tasks": true,
+    "enable_lsp_tasks": true,
   }
 }
 ```