doc: rename datatypes to data types

PR-URL: #39209
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Harshitha K P <harshitha014@gmail.com>

doc/guides/adding-new-napi-api.md

@@ -11,7 +11,7 @@ Node-API.
   * **Must** return `napi_status`.
   * **Should** consume `napi_env`.
   * **Must** operate only on primitive data types, pointers to primitive
-    datatypes or opaque handles.
+    data types or opaque handles.
   * **Must** be a necessary API and not a nice to have. Convenience APIs
     belong in node-addon-api.
   * **Must** not change the signature of an existing Node-API API or break