DOC: fix headers to avoid warnings

Author: jorisvandenbossche

doc/source/ecosystem.rst

@@ -19,22 +19,22 @@ We'd like to make it easier for users to find these project, if you know of othe
 substantial projects that you feel should be on this list, please let us know.
 
 `Statsmodels <http://statsmodels.sourceforge.net>`__
------------
+----------------------------------------------------
 
 Statsmodels is the prominent python "statistics and econometrics library" and it has
 a long-standing special relationship with pandas. Statsmodels provides powerful statistics,
 econometrics, analysis and modeling functionality that is out of pandas' scope.
 Statsmodels leverages pandas objects as the underlying data container for computation.
 
 `Vincent <https://github.com/wrobstory/vincent>`__
--------
+--------------------------------------------------
 
 The `Vincent <https://github.com/wrobstory/vincent>`__ project leverages `Vega <https://github.com/trifacta/vega>`__
 (that in turn, leverages `d3 <http://d3js.org/>`__) to create plots . It has great support
 for pandas data objects.
 
 `yhat/ggplot <https://github.com/yhat/ggplot>`__
------------
+------------------------------------------------
 
 Hadley Wickham's `ggplot2 <http://ggplot2.org/>`__ is a foundational exploratory visualization package for the R language.
 Based on `"The Grammer of Graphics" <http://www.cs.uic.edu/~wilkinson/TheGrammarOfGraphics/GOG.html>`__ it
@@ -46,7 +46,7 @@ progressing quickly in that direction.
 
 
 `Seaborn <https://github.com/mwaskom/seaborn>`__
--------
+------------------------------------------------
 
 Although pandas has quite a bit of "just plot it" functionality built-in, visualization and
 in particular statistical graphics is a vast field with a long tradition and lots of ground
@@ -56,7 +56,7 @@ more advanced types of plots then those offered by pandas.
 
 
 `Geopandas <https://github.com/kjordahl/geopandas>`__
----------
+------------------------------------------------------
 
 Geopandas extends pandas data objects to include geographic information which support
 geometric operations. If your work entails maps and geographical coordinates, and