Add entry to CREDITS.TXT for propagate_const


git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@273123 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/CREDITS.TXT b/CREDITS.TXT
index 1cf713a..ceb12c4 100644
--- a/CREDITS.TXT
+++ b/CREDITS.TXT
@@ -37,6 +37,10 @@
 E: marshall@idio.com
 D: C++14 support, patches and bug fixes.
 
+N: Jonathan B Coe
+E: jbcoe@me.com
+D: Implementation of propagate_const.
+
 N: Eric Fiselier
 E: eric@efcs.ca
 D: LFTS support, patches and bug fixes.