DOC: Remove conda-forge badge

We have work to do to support `itk` on conda-forge -- remove
instructions until that has been addressed.

Author: thewtex

README.rst

@@ -5,10 +5,6 @@ itkwidgets
     :target: https://pypi.python.org/pypi/itkwidgets
     :alt: PyPI version
 
-.. image:: https://img.shields.io/conda/vn/conda-forge/itkwidgets.svg
-    :target: https://anaconda.org/conda-forge/itkwidgets
-    :alt: Conda version
-
 .. image:: https://img.shields.io/npm/v/itkwidgets/latest
     :target: https://www.npmjs.com/package/itkwidgets
     :alt: npm
@@ -138,10 +134,6 @@ To install the widgets for the Jupyter Notebook with pip::
 
   pip install itkwidgets
 
-or with conda::
-
-  conda install -c conda-forge itkwidgets
-
 For Jupyter Lab, additionally run::
 
   jupyter labextension install @jupyter-widgets/jupyterlab-manager jupyter-matplotlib jupyterlab-datawidgets itkwidgets