Update README.md and CONTRIBUTING.md: repoman -> pkgcheck.

CONTRIBUTING.md

@@ -3,7 +3,13 @@ requests. So, go over to GitHub and fork this repository:
 
 [https://github.com/fritteli/gentoo-overlay](https://github.com/fritteli/gentoo-overlay)
 
-Then change whatever you want and send me the pull request. If you want, you can
+After you're done, please make sure that your changes don't upset
-also create an issue along with it. But you don't have to.
+[`pkgcheck`](https://wiki.gentoo.org/wiki/Pkgcheck). Run the following
+command and fix warnings and errors:
+
+	pkgcheck scan --net .
+
+Then send me the pull request. If you want, you can also create an issue along
+with it. But you don't have to.
 
 Thank you for your help!

README.md

@@ -42,9 +42,9 @@ If you find a bug in an ebuild, encounter a build error or would like me to add
 
 ## Contributing
 
-I gladly accept pull requests for bugs or new ebuilds. Before opening a pull request, please make sure your changes don't upset [`repoman`](https://wiki.gentoo.org/wiki/Repoman). Run the following command and fix warnings and errors:
+I gladly accept pull requests for bugs or new ebuilds. Before opening a pull request, please make sure your changes don't upset [`pkgcheck`](https://wiki.gentoo.org/wiki/Pkgcheck). Run the following command and fix warnings and errors:
 
-	repoman -x -p
+	pkgcheck scan --net .
 
 ## Maintainers