doc: fix syntax error in nested conditions example

PR-URL: nodejs#41205
Reviewed-By: Guy Bedford <[email protected]>
Reviewed-By: Colin Ihrig <[email protected]>
Reviewed-By: Tobias Nießen <[email protected]>
Reviewed-By: Michael Dawson <[email protected]>
Reviewed-By: Antoine du Hamel <[email protected]>
Reviewed-By: Rich Trott <[email protected]>
Reviewed-By: Richard Lau <[email protected]>
Reviewed-By: Adrian Estrada <[email protected]>

doc/api/packages.md

@@ -566,7 +566,7 @@ use in Node.js but not the browser:
       "import": "./feature-node.mjs",
       "require": "./feature-node.cjs"
     },
-    "default": "./feature.mjs",
+    "default": "./feature.mjs"
   }
 }
 ```