fix typo

Author: sokra

README.md

@@ -49,8 +49,8 @@ var wp = new Watchpack({
 	// ignored: "string" - a glob pattern for files or folders that should not be watched
 	// ignored: ["string", "string"] - multiple glob patterns that should be ignored
 	// ignored: /regexp/ - a regular expression for files or folders that should not be watched
-	// ignored: (entry) => boolean - an arbirary function which must return truthy to ignore an entry
-	// For all cases expect the arbirary function the path will have path separator normalized to '/'.
+	// ignored: (entry) => boolean - an arbitrary function which must return truthy to ignore an entry
+	// For all cases expect the arbitrary function the path will have path separator normalized to '/'.
 	// All subdirectories are ignored too
 });