doc: clarify napi_property_attributes text

* Rearrange sentence to avoid ambiguity whether the entire sentence
  applies to a method in a JS class or just the "but not" part
* Use serial comma
* Correct spelling of _configurable_

PR-URL: #35253
Reviewed-By: Chengzhong Wu <legendecas@gmail.com>
Reviewed-By: Michael Dawson <midawson@redhat.com>
Reviewed-By: Gerhard Stöbich <deb2001-github@yahoo.de>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>

Author: Trott

doc/api/n-api.md

@@ -3789,10 +3789,10 @@ They can be one or more of the following bitflags:
 * `napi_static`: The property will be defined as a static property on a class as
   opposed to an instance property, which is the default. This is used only by
   [`napi_define_class`][]. It is ignored by `napi_define_properties`.
-* `napi_default_method`: The property is configureable, writeable but not
-  enumerable like a method in a JS class.
-* `napi_default_property`: The property is writable, enumerable and configurable
-  like a property set via JS code `obj.key = value`.
+* `napi_default_method`: Like a method in a JS class, the property is
+  configurable and writeable, but not enumerable.
+* `napi_default_property`: Like a property set via assignment in JavaScript, the
+  property is writable, enumerable, and configurable.
 
 #### napi_property_descriptor