Add xclim and CLISOPS to list of projects that use Pooch (#445)

Add two projects that are currently using `pooch`:

- `xclim`: A climate science operational toolkit for performing analyses
and statistical adjustments to CF-compliant climate data.
- `CLISOPS`: A data reduction library used to support averaging,
regridding, and subsetting of climate and other data.

README.md

@@ -79,6 +79,8 @@ Are you a **scientist** or researcher? Pooch can help you too!
 [RosettaSciIO](https://github.com/hyperspy/rosettasciio),
 [eXSpy](https://github.com/hyperspy/exspy),
 [SPLASH](https://github.com/Adam-Boesky/astro_SPLASH)
+[xclim](https://github.com/Ouranosinc/xclim)
+[CLISOPS](https://github.com/roocs/clisops)
 
 
 > If you're using Pooch, **send us a pull request** adding your project to the list.