fix URLs

README.md

@@ -4,7 +4,7 @@ NIFTy - Numerical Information Field Theory
 [![coverage report](https://gitlab.mpcdf.mpg.de/ift/NIFTy/badges/NIFTy_5/coverage.svg)](https://gitlab.mpcdf.mpg.de/ift/NIFTy/commits/NIFTy_5)
 
 **NIFTy** project homepage:
-[http://ift.pages.mpcdf.de/NIFTy](http://ift.pages.mpcdf.de/NIFTy)
+[http://ift.pages.mpcdf.de/nifty](http://ift.pages.mpcdf.de/nifty)
 
 Summary
 -------
@@ -116,7 +116,7 @@ following command in the repository root:
 ### First Steps
 
 For a quick start, you can browse through the [informal
-introduction](http://ift.pages.mpcdf.de/NIFTy/code.html) or
+introduction](http://ift.pages.mpcdf.de/nifty/code.html) or
 dive into NIFTy by running one of the demonstrations, e.g.:
 
     python3 demos/getting_started_1.py
@@ -130,7 +130,7 @@ phrase such as the following:
 > "Some of the results in this publication have been derived using the
 > NIFTy package [(https://gitlab.mpcdf.mpg.de/ift/NIFTy)](https://gitlab.mpcdf.mpg.de/ift/NIFTy)"
 
-and a citation to one of the [publications](http://ift.pages.mpcdf.de/NIFTy/citations.html).
+and a citation to one of the [publications](http://ift.pages.mpcdf.de/nifty/citations.html).
 
 
 ### Licensing terms