message: Add link to cubical notebook
diff: @@ -47,8 +47,8 @@ be a set of two elements).
  For further details and theory of cubical complexes, please consult :cite:`kaczynski2004computational` as well as the
  following paper :cite:`peikert2012topological`.
  -Data structure.
  ----------------
  +Data structure
  +--------------
  The implementation of Cubical complex provides a representation of complexes that occupy a rectangular region in
  :math:`\mathbb{R}^n`. This extra assumption allows for a memory efficient way of storing cubical complexes in a form
  @@ -77,8 +77,8 @@ Knowing the sizes of the bitmap, by a series of modulo operation, we can determi
  present in the product that gives the cube :math:`C`. In a similar way, we can compute boundary and the coboundary of
  each cube. Further details can be found in the literature.
  -Input Format.
  --------------
  +Input Format
  +------------
  In the current implantation, filtration is given at the maximal cubes, and it is then extended by the lower star
  filtration to all cubes. There are a number of constructors that can be used to construct cubical complex by users
  @@ -108,8 +108,8 @@ the program output is:
  Cubical complex is of dimension 2 - 49 simplices.
  -Periodic boundary conditions.
  ------------------------------
  +Periodic boundary conditions
  +----------------------------
  Often one would like to impose periodic boundary conditions to the cubical complex (cf.
  :doc:`periodic_cubical_complex_ref`).
  @@ -154,7 +154,13 @@ the program output is:
  Periodic cubical complex is of dimension 2 - 42 simplices.
  -Examples.
  ----------
  +Examples
  +--------
  End user programs are available in python/example/ folder.
  +
  +Tutorial
  +--------
  +
  +This `notebook <https://github.com/GUDHI/TDA-tutorial/blob/master/Tuto-GUDHI-cubical-complexes.ipynb>`_
  +explains how to represent sublevels sets of functions using cubical complexes.
  \ No newline at end of file
  