Regex: moved and deleted content from the "Patterns and flags".

1. Moved some content that was not pertinent.
2. Deleted a repetition.

Closes 962.

Author: luc4leone

9-regular-expressions/01-regexp-introduction/article.md

@@ -1,13 +1,5 @@
 # Patterns and flags
 
-Regular expressions is a powerful way of searching and replacing inside a string.
-
-In JavaScript regular expressions are implemented using objects of a built-in `RegExp` class and integrated with strings.
-
-Please note that regular expressions vary between programming languages. In this tutorial we concentrate on JavaScript. Of course there's a lot in common, but they are a somewhat different in Perl, Ruby, PHP etc.
-
-## Regular expressions
-
 A regular expression (also "regexp", or just "reg") consists of a *pattern* and optional *flags*.
 
 There are two syntaxes to create a regular expression object.

9-regular-expressions/index.md

@@ -1,3 +1,7 @@
 # Regular expressions
 
 Regular expressions is a powerful way of doing search and replace in strings.
+
+In JavaScript regular expressions are implemented using objects of a built-in `RegExp` class and integrated with strings.
+
+Please note that regular expressions vary between programming languages. In this tutorial we concentrate on JavaScript. Of course there's a lot in common, but they are a somewhat different in Perl, Ruby, PHP etc.