Added info about pkg-config being an optional requirement

kitsemets · kitsemets · commit 2d3f9d8e551c · 2015-03-07T12:44:32.000+02:00
diff --git a/docs/install.rst b/docs/install.rst
@@ -17,7 +17,7 @@ Requirements
 - Libgit2 v0.22.x
 - cffi 0.8.1+
 - Libssh2, optional, used for SSH network operations.
-- pkg-config
+- pkg-config, optional, used for SSH network operations.
 
 .. warning::
 
