Remove NEWS.md from .Rbuildignore, now supported by CRAN

Change-Id: Ie91a42f4961f26943f63d034c4ef525812efad19
diff --git a/.Rbuildignore b/.Rbuildignore
index 6101f5b..6806493 100644
--- a/.Rbuildignore
+++ b/.Rbuildignore
@@ -1,5 +1,4 @@
 ^.*\.Rproj$
 ^\.Rproj\.user$
 ^Readme.md
-^NEWS.md
 ^cran-comments.md