Fixing http://issues.roundup-tracker.org/issue2550859 which reports a 404 error accessing spec.html reference in the developer.html page. Changed references to spec.html in developers.txt and installation.txt to point to design.html since there is no spec.html. I did track down a copy of what I think is supposed to be spec.html from google cache of: http://zesty.ca/sc-roundup.html. It is a snapshot of the page as it appeared on Dec 4, 2014 22:56:45 GMT obtained via: http://webcache.googleusercontent.com/search?q=cache:Zyw8ZjphH2AJ:zesty.ca/sc-roundup.html The copy of spec.html is missing images (www.lfw.org which hosted the images seems to be gone). I left the reference to spec.html in design.txt (aka design.html) rather than having it point to itself. Also the text surrounding the reference to spec.html discussses rationale and things that are misssing from design.html. I am not sure what can be done to retrieve the real spec.html with images etc, or exactly how to handle the spec.html reference in design.html.

--- a/doc/developers.txt	Tue Nov 25 16:31:06 2014 +0100
+++ b/doc/developers.txt	Sat Dec 06 23:18:40 2014 -0500
@@ -410,7 +410,7 @@
 `PO`_ file is changed.
 
 .. _`Customising Roundup`: customizing.html
-.. _`Roundup's Design Document`: spec.html
+.. _`Roundup's Design Document`: design.html
 .. _`implementation notes`: implementation.html