DOC: Fix hyperlink in README. (#483)

Author: absolutelyNoWarranty

README.rst

@@ -44,7 +44,7 @@ Documentation
 Installation documentation, API documentation, and examples can be found on the
 documentation_.
 
-.. _documentation: http://contrib.scikit-learn.org/imbalanced-learn/
+.. _documentation: https://imbalanced-learn.readthedocs.io/en/stable/
 
 Installation
 ------------
@@ -170,7 +170,7 @@ Below is a list of the methods currently implemented in this module.
 
 The different algorithms are presented in the sphinx-gallery_.
 
-.. _sphinx-gallery: http://contrib.scikit-learn.org/imbalanced-learn/stable/auto_examples/index.html
+.. _sphinx-gallery: https://imbalanced-learn.readthedocs.io/en/stable/auto_examples/index.html
 
 
 References:
@@ -206,4 +206,4 @@ References:
 
 .. [15] : H. He, Y. Bai, E. A. Garcia, S. Li, “ADASYN: Adaptive synthetic sampling approach for imbalanced learning,” In Proceedings of the 5th IEEE International Joint Conference on Neural Networks, pp. 1322-1328, 2008. [`pdf <https://pdfs.semanticscholar.org/4823/4756b7cf798bfeb47328f7c5d597fd4838c2.pdf>`_] [`bib <references.bib#L62>`_] 
 
-.. [16] : C. Chao, A. Liaw, and L. Breiman. "Using random forest to learn imbalanced data." University of California, Berkeley 110 (2004): 1-12.
+.. [16] : C. Chao, A. Liaw, and L. Breiman. "Using random forest to learn imbalanced data." University of California, Berkeley 110 (2004): 1-12.