📝 Add change summary

Author: rdbisme

CHANGES.txt

@@ -12,6 +12,10 @@ NOTE: Python 3.6 support is deprecated and will be dropped in a future release.
 
 RELEASE  VERSION/DATE TO BE FILLED IN LATER
 
+  From Ruben Di Battista: 
+    - Expose `extra_libs` kwarg in the `CheckLibWithHeader` and forward it downstream
+      to `CheckLib`
+
   From Joseph Brill:
     - Added error handling when creating MSVC detection debug log file specified by
       SCONS_MSCOMMON_DEBUG.

RELEASE.txt

@@ -25,6 +25,7 @@ DEPRECATED FUNCTIONALITY
 
 CHANGED/ENHANCED EXISTING FUNCTIONALITY
 ---------------------------------------
+- Expose the `extra_libs` keyword argument in `CheckLibWithHeader`
 
 - List modifications to existing features, where the previous behavior
   wouldn't actually be considered a bug