[librsvg] Update NEWS

[Federico Mena Quintero <federico src gnome org>]

commit e438042ad64f010f5f8f18a697feade52b511092
Author: Federico Mena Quintero <federico gnome org>
Date:   Wed Dec 18 19:51:18 2019 -0600

    Update NEWS

 NEWS | 8 ++++++++
 1 file changed, 8 insertions(+)
---
diff --git a/NEWS b/NEWS
index e365c3a4..e4a227df 100644
--- a/NEWS
+++ b/NEWS
@@ -1,3 +1,11 @@
+Version 2.47.2
+
+- Handling of the "result", "in", "in2" attributes in filter
+  primitives is slightly stricter now, and spec compliant.  Their
+  arguments must be of type CSS custom-ident, so "default", "inherit",
+  "initial", and "unset" are disallowed.  Most SVGs should still work
+  fine.
+
 Version 2.47.1
 
 - Librsvg no longer depends on libcroco!  It now does all CSS