Merge pull request #670 from pietroalbini/codeowners

Allow team leads posting Inside Rust blog posts

Author: pietroalbini

.github/CODEOWNERS

@@ -1,3 +1,4 @@
 * @rust-lang/website
 posts/* @rust-lang/core
-posts/inside-rust/* @rust-lang/website @rust-lang/core
+posts/inside-rust/* @rust-lang/leads @rust-lang/core
+.github/CODEOWNERS @rust-lang/core