[docs] fix link to attr_line.hh

ARCHITECTURE.md

@@ -99,7 +99,7 @@ primitives:
 
 - [view_curses](src/view_curses.hh) - Provides the basics for text roles, which
   allows for themes to color and style text. The `mvwattrline()` function does
-  all the heavy lifting of drawing ["attributed" lines](src/attr_line.hh),
+  all the heavy lifting of drawing ["attributed" lines](src/base/attr_line.hh),
   which are strings that have attributes associated with a given range of
   characters.
 - [listview_curses](src/listview_curses.hh) - Displays a list of items that are