update outdated links to example data (#289)

Hey @gigony, I updated a couple of outdated links here.

You mention that TIFF files were created by conversion from .svs. What package/tool did you use to do the conversion?

Authors:
  - Gregory Lee (https://github.com/grlee77)

Approvers:
  - Gigon Bae (https://github.com/gigony)
  - https://github.com/jakirkham

URL: #289

notebooks/input/README.md

@@ -5,8 +5,8 @@ TUPAC-TR-488.svs and TUPAC-TR-467.svs are breast cancer cases from the dataset
 of Tumor Proliferation Assessment Challenge 2016 (TUPAC16 | MICCAI Grand Challenge) which are publicly
 available through [The Cancer Genome Atlas (TCGA)](https://www.cancer.gov/about-nci/organization/ccg/research/structural-genomics/tcga).
 
-- Website: http://tupac.tue-image.nl/node/3
-- Data link: https://drive.google.com/drive/u/0/folders/0B--ztKW0d17XYlBqOXppQmw0M2M
+- Website: https://tupac.grand-challenge.org
+- Data link: https://tupac.grand-challenge.org/Dataset/
   - TUPAC-TR-467.svs : https://portal.gdc.cancer.gov/files/575c0465-c4bc-4ea7-ab63-ba48aa5e374b
   - TUPAC-TR-488.svs : https://portal.gdc.cancer.gov/files/e27c87c9-e163-4d55-8f27-4cc7dfca08d8
 - License: CC BY 3.0 (https://wiki.cancerimagingarchive.net/display/Public/TCGA-BRCA#3539225f58e64731d8e47d588cedd99d300d5d6)