Merge branch 'master' of github.com:javascript-tutorial/en.javascript.info into sync-e074a5f8

Author: iliakan

1-js/02-first-steps/08-operators/article.md

@@ -428,7 +428,7 @@ The list of operators:
 - RIGHT SHIFT ( `>>` )
 - ZERO-FILL RIGHT SHIFT ( `>>>` )
 
-These operators are used very rarely, when we need to fiddle with numbers on the very lowest (bitwise) level. We won't need these operators any time soon, as web development has little use of them, but in some special areas, such as cryptography, they are useful. You can read the [Bitwise Operators](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Operators/Bitwise_Operators) article on MDN when a need arises.
+These operators are used very rarely, when we need to fiddle with numbers on the very lowest (bitwise) level. We won't need these operators any time soon, as web development has little use of them, but in some special areas, such as cryptography, they are useful. You can read the [Bitwise Operators](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Expressions_and_Operators#Bitwise) chapter on MDN when a need arises.
 
 ## Comma
 

1-js/07-object-properties/01-property-descriptors/article.md

@@ -227,32 +227,42 @@ To be precise, non-configurability imposes several restrictions on `defineProper
 3. Can't change `writable: false` to `true` (the other way round works).
 4. Can't change `get/set` for an accessor property (but can assign them if absent).
 
-Here we are making `user.name` a "forever sealed" constant:
+**The idea of "configurable: false" is to prevent changes of property flags and its deletion, while allowing to change its value.**
+
+Here `user.name` is non-configurable, but we can still change it (as it's writable):
 
 ```js run
-let user = { };
+let user = {
+  name: "John"
+};
+
+Object.defineProperty(user, "name", {
+  configurable: false
+});
+
+user.name = "Pete"; // works fine
+delete user.name; // Error
+```
+
+And here we make `user.name` a "forever sealed" constant:
+
+```js run
+let user = {
+  name: "John"
+};
 
 Object.defineProperty(user, "name", {
-  value: "John",
   writable: false,
   configurable: false
 });
 
-*!*
 // won't be able to change user.name or its flags
 // all this won't work:
-//   user.name = "Pete"
-//   delete user.name
-//   Object.defineProperty(user, "name", { value: "Pete" })
-Object.defineProperty(user, "name", {writable: true}); // Error
-*/!*
+user.name = "Pete";
+delete user.name;
+Object.defineProperty(user, "name", { value: "Pete" });
 ```
 
-```smart header="\"Non-configurable\" doesn't mean \"non-writable\""
-Notable exception: a value of non-configurable, but writable property can be changed.
-
-The idea of `configurable: false` is to prevent changes to property flags and its deletion, not changes to its value.
-```
 
 ## Object.defineProperties