Pause building PDF and zipping notebooks

The PDF was breaking the Travis build and needs investigation.
The zip containing the notebooks is not linked from anywhere, can
be retrieved from GitHub and is taking up a lot of space.

Author: ageorgou

Makefile

@@ -63,7 +63,7 @@ master.zip: Makefile
 	rm -f master.zip
 	wget https://github.com/UCL-RITS/indigo-jekyll/archive/master.zip
 
-ready: indigo $(HTMLS) notes.pdf notebooks.zip
+ready: indigo $(HTMLS) # notes.pdf notebooks.zip
 
 indigo-jekyll-master: Makefile master.zip
 	rm -rf indigo-jekyll-master

index.md

@@ -137,4 +137,5 @@ program. That means that you may find supplementary python content useful.
 
 You can find the course notes as HTML via the navigation bar to the left.
 
-The [notes](notes.pdf) are also available in  a printable pdf format.
+The [notes](notes.pdf) are also available in a printable pdf format.
+(**temporarily unavailable!**)