ES6 & Beyond (ch7.md): Broken links on Regex section

Links pointing to people.mozilla.org are currently being used. However, people.mozilla.org has been discontinued.
The links were pointing to ES6/ES2015 sections. I updated the links to use ecma-international.org. Each link should point to its corresponding section on the specification

es6 & beyond/ch7.md

@@ -323,20 +323,20 @@ There are four well known symbols that can be overridden for regular expression
 
 * `@@match`: The `Symbol.match` value of a regular expression is the method used to match all or part of a string value with the given regular expression. It's used by `String.prototype.match(..)` if you pass it a regular expression for the pattern matching.
 
-   The default algorithm for matching is laid out in section 21.2.5.6 of the ES6 specification (https://people.mozilla.org/~jorendorff/es6-draft.html#sec-regexp.prototype-@@match). You could override this default algorithm and provide extra regex features, such as look-behind assertions.
+   The default algorithm for matching is laid out in section 21.2.5.6 of the ES6 specification (http://www.ecma-international.org/ecma-262/6.0/#sec-regexp.prototype-@@match). You could override this default algorithm and provide extra regex features, such as look-behind assertions.
 
    `Symbol.match` is also used by the `isRegExp` abstract operation (see the note in "String Inspection Functions" in Chapter 6) to determine if an object is intended to be used as a regular expression. To force this check to fail for an object so it's not treated as a regular expression, set the `Symbol.match` value to `false` (or something falsy).
 * `@@replace`: The `Symbol.replace` value of a regular expression is the method used by `String.prototype.replace(..)` to replace within a string one or all occurrences of character sequences that match the given regular expression pattern.
 
-   The default algorithm for replacing is laid out in section 21.2.5.8 of the ES6 specification (https://people.mozilla.org/~jorendorff/es6-draft.html#sec-regexp.prototype-@@replace).
+   The default algorithm for replacing is laid out in section 21.2.5.8 of the ES6 specification (http://www.ecma-international.org/ecma-262/6.0/#sec-regexp.prototype-@@replace).
 
    One cool use for overriding the default algorithm is to provide additional `replacer` argument options, such as supporting `"abaca".replace(/a/g,[1,2,3])` producing `"1b2c3"` by consuming the iterable for successive replacement values.
 * `@@search`: The `Symbol.search` value of a regular expression is the method used by `String.prototype.search(..)` to search for a sub-string within another string as matched by the given regular expression.
 
-   The default algorithm for searching is laid out in section 21.2.5.9 of the ES6 specification (https://people.mozilla.org/~jorendorff/es6-draft.html#sec-regexp.prototype-@@search).
+   The default algorithm for searching is laid out in section 21.2.5.9 of the ES6 specification (http://www.ecma-international.org/ecma-262/6.0/#sec-regexp.prototype-@@search).
 * `@@split`: The `Symbol.split` value of a regular expression is the method used by `String.prototype.split(..)` to split a string into sub-strings at the location(s) of the delimiter as matched by the given regular expression.
 
-   The default algorithm for splitting is laid out in section 21.2.5.11 of the ES6 specification (https://people.mozilla.org/~jorendorff/es6-draft.html#sec-regexp.prototype-@@split).
+   The default algorithm for splitting is laid out in section 21.2.5.11 of the ES6 specification (http://www.ecma-international.org/ecma-262/6.0/#sec-regexp.prototype-@@split).
 
 Overriding the built-in regular expression algorithms is not for the faint of heart! JS ships with a highly optimized regular expression engine, so your own user code will likely be a lot slower. This kind of meta programming is neat and powerful, but it should only be used in cases where it's really necessary or beneficial.