Merge pull request #12 from marimeireles/patch-1

Update install.rst

Author: ashb

docs/install.rst

@@ -6,6 +6,10 @@ This extension is tested on python 2.7 and 3.3+.
 The package is available in the Python Package Index::
 
     pip install sphinx-argparse
+    
+And also in conda-forge::
+
+    mamba -c conda-forge install sphinx-argparse
 
 Enable the extension in your sphinx config::