doc: fix syntax error in nested conditions example

PR-URL: #41205
Reviewed-By: Guy Bedford <guybedford@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Michael Dawson <midawson@redhat.com>
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Richard Lau <rlau@redhat.com>
Reviewed-By: Adrian Estrada <edsadr@gmail.com>

Author: Andarist

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"
   }
 }
 ```