feat: update package.json

Author: Neerajpathak07

lib/node_modules/@stdlib/number/float32/base/signbit/package.json

@@ -14,11 +14,14 @@
     }
   ],
   "main": "./lib",
+  "gypfile": true,
   "directories": {
     "benchmark": "./benchmark",
     "doc": "./docs",
     "example": "./examples",
+    "include": "./include",
     "lib": "./lib",
+    "src": "./src",
     "test": "./test"
   },
   "types": "./docs/types",