fix: fix online manual imag and doc links

Author: Tieqiong

Diff for: doc/manual/html/readme.txt

@@ -1446,7 +1446,7 @@ the comments in the script for detailed explanation.
 To learn more about the tui module and about the objects
 and functions that it returns, please see the API
 documentation for diffpy.pdfgui at
-@url{http://docs.danse.us/diffraction/diffpy.pdfgui/}.
+@url{https://diffpy.github.io/diffpy.pdfgui}.
 
 Feel free to ask at the
 @url{https://groups.google.com/d/forum/diffpy-users, diffpy-users}

Diff for: doc/source/images/Makefile renamed to doc/manual/images/Makefile

@@ -158,7 +158,7 @@
 # Add any extra paths that contain custom files (such as robots.txt or
 # .htaccess) here, relative to this directory. These files are copied
 # directly to the root of the documentation.
-# html_extra_path = []
+html_extra_path = ["../manual"]
 
 # If not '', a 'Last updated on:' timestamp is inserted at every page bottom,
 # using the given strftime format.