DOC Add conda-forge badge and installation option (#48)

README.rst

@@ -1,11 +1,14 @@
 pgeocode
 ========
 
-|pypi| |rdfd| |GHactions|
+|pypi| |condaforge| |rdfd| |GHactions|
 
 .. |pypi| image:: https://img.shields.io/pypi/v/pgeocode.svg
    :target: https://pypi.org/project/pgeocode/
 
+.. |condaforge| image:: https://img.shields.io/conda/vn/conda-forge/pgeocode.svg
+   :target: https://anaconda.org/conda-forge/pgeocode
+
 .. |rdfd| image:: https://readthedocs.org/projects/pgeocode/badge/?version=latest
     :target: http://pgeocode.readthedocs.io/
 
@@ -34,6 +37,12 @@ pgeocode requires Python 3.6+ as well as ``numpy`` and ``pandas`` packages. It c
 
     pip install pgeocode
 
+or
+
+.. code::
+
+    conda install -c conda-forge pgeocode
+
 Quickstart
 ----------