Fixed logo path for latex latex build on rtd.

docs/user/py/conf.py

@@ -201,7 +201,7 @@ latex_documents = [
 
 # The name of an image file (relative to this directory) to place at the top of
 # the title page.
-latex_logo = 'images/moose_logo.png'
+latex_logo = '../../images/moose_logo.png'
 
 # For "manual" documents, if this is true, then toplevel headings are parts,
 # not chapters.