Fix typo (#257)

mainpulate -> manipulate

pollen/scribblings/story.scrbl

@@ -16,7 +16,7 @@ That's no longer true. The web is now more than 20 years old. During that time,
 
 But one part hasn't improved much: the way we make web pages. Over the years, tools promising to simplify web development have come and mostly gone — from @link["http://www.macobserver.com/reviews/pagemill2.shtml"]{PageMill} to @link["http://www.adobe.com/products/dreamweaver.html"]{Dreamweaver} to @link["http://www.squarespace.com"]{Squarespace}. Meanwhile, serious web jocks have remained loyal to the original HTML power tool: the humble text editor. 
 
-In one way, this makes sense. Web pages are made mostly of text-based data — HTML, CSS, JavaScript, and so on — and the simplest way to mainpulate this data is with a text editor. While HTML and CSS are not programming languages — you can't even compute 1 + 1 — they lend themselves to semantic and logical structure that's most easily expressed by editing them as text. Furthermore, text-based editing makes debugging and performance improvements easier.
+In one way, this makes sense. Web pages are made mostly of text-based data — HTML, CSS, JavaScript, and so on — and the simplest way to manipulate this data is with a text editor. While HTML and CSS are not programming languages — you can't even compute 1 + 1 — they lend themselves to semantic and logical structure that's most easily expressed by editing them as text. Furthermore, text-based editing makes debugging and performance improvements easier.
 
 But text-based editing is also limited. Though the underlying description of a web page is notionally human-readable, it's optimized to be readable by other software — namely, web browsers. HTML in particular is verbose and easily mistyped. And isn't it fatally dull to manage all the boilerplate, like surrounding every paragraph with @code{<p>...</p>}? Yes, it is.