Update information about NanumBarunGothic

Author: ColinPitrat

src/librustdoc/html/static/COPYRIGHT.txt

@@ -47,8 +47,18 @@ included, and carry their own copyright notices and license terms:
 
 * Nanum Barun Gothic Font (NanumBarunGothic.woff2)
 
-    Copyright 2017 NAVER, free for personal and commercial use.
+    Copyright 2010, NAVER Corporation (http://www.nhncorp.com)
+    with Reserved Font Name Nanum, Naver Nanum, NanumGothic, Naver NanumGothic,
+    NanumMyeongjo, Naver NanumMyeongjo, NanumBrush, Naver NanumBrush, NanumPen,
+    Naver NanumPen, Naver NanumGothicEco, NanumGothicEco,
+    Naver NanumMyeongjoEco, NanumMyeongjoEco, Naver NanumGothicLight,
+    NanumGothicLight, NanumBarunGothic, Naver NanumBarunGothic.
+
     https://hangeul.naver.com/2017/nanum
+    https://github.com/hiun/NanumBarunGothic
+
+    Licensed under the SIL Open Font License, Version 1.1.
+    See NanumBarunGothic-LICENSE.txt.
 
 * Rust logos (rust-logo.svg, favicon.svg, favicon-32x32.png)