[librsvg: 3/4] Update NEWS

[Federico Mena Quintero <federico src gnome org>]

commit 7000f0bece6249ec268a22dd23a63b162ba5ae2e
Author: Federico Mena Quintero <federico gnome org>
Date:   Mon Sep 14 14:10:17 2020 -0500

    Update NEWS

 NEWS | 6 ++++++
 1 file changed, 6 insertions(+)
---
diff --git a/NEWS b/NEWS
index b5964bf6..7d0de2d0 100644
--- a/NEWS
+++ b/NEWS
@@ -1,3 +1,9 @@
+Version 2.51.0
+
+- #623 - The pkg-config files (*.pc) do not define the 'svgz_supported' and
+  'css_supported' variables anymore.  These variables were hardcoded
+  to 'true' and unchanged since 2011.
+
 Version 2.49.5
 
 - #607 - Support the mix-blend-mode property from SVG2 and the