trivial spelling fixes

transfersh-web/scripts/showdown.js

@@ -106,7 +106,7 @@ this.makeHtml = function(text) {
 
 	// attacklab: Replace ~ with ~T
 	// This lets us use tilde as an escape char to avoid md5 hashes
-	// The choice of character is arbitray; anything that isn't
+	// The choice of character is arbitrary; anything that isn't
     // magic in Markdown will work.
 	text = text.replace(/~/g,"~T");