fix typo in CONTRIBUTING.md

CONTRIBUTING.md

@@ -28,7 +28,7 @@ Look at [mkdocs serve](https://www.mkdocs.org/user-guide/cli/#mkdocs-serve) for
 ### Operating system specific installation instructions?
 
 There are a lot of targets out there.  Today we have docs that are Ubuntu biased
-and I know that there are a lot flavors of Linux.  Rather than expand the README
+and I know that there are a lot of flavors of Linux.  Rather than expand the README
 with instructions for those, please translate the instructions into steps that
 can be run in the [`get-deps`](https://github.com/wez/wezterm/blob/master/get-deps)
 script.