Update URL redirects in index.rst

Author: partev

docs/index.rst

@@ -110,7 +110,7 @@ as we discuss below.
 More information can be found in these books:
 
    * "Machine Learning: Advanced Topics", K. Murphy, MIT Press 2023. Available at https://probml.github.io/pml-book/book2.html.
-   * "Bayesian Filtering and Smoothing, Second Edition", S. Särkkä and L. Svensson, Cambridge University Press, 2023. Available at http://users.aalto.fi/~ssarkka/pub/bfs_book_2023_online.pdf
+   * "Bayesian Filtering and Smoothing, Second Edition", S. Särkkä and L. Svensson, Cambridge University Press, 2023. Available at https://users.aalto.fi/~ssarkka/pub/bfs_book_2023_online.pdf
 
 Quickstart
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@@ -262,7 +262,7 @@ Related Libraries
 .. _linderman-ssm-numpy: https://github.com/lindermanlab/ssm
 .. _mattjj-pyhsmm: https://github.com/mattjj/pyhsmm
 .. _mattjj-pylds: https://github.com/mattjj/pylds
-.. _optax: https://github.com/deepmind/optax
+.. _optax: https://github.com/google-deepmind/optax
 .. _pgm-jax: https://github.com/probml/pgm-jax
 .. _pykalman: https://pykalman.github.io/
 .. _sarkka-parallel-non-linear-gaussian-smoothers: https://github.com/EEA-sensors/parallel-non-linear-gaussian-smoothers