Added "Michael Park" to `CREDITS.TXT`.

Summary: Test commit + give myself credit.

Reviewers: EricWF

Differential Revision: https://reviews.llvm.org/D28431

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@291344 91177308-0d34-0410-b5e6-96231b3b80d8

CREDITS.TXT

@@ -80,6 +80,10 @@ N: Andrew Morrow
 E: andrew.c.morrow@gmail.com
 D: Minor patches and Linux fixes.
 
+N: Michael Park
+E: mpark@apache.org
+D: Implementation of <variant>.
+
 N: Arvid Picciani
 E: aep at exys dot org
 D: Minor patches and musl port.