[CHANGELOG.md] updated changelog

Author: chrissimpkins

CHANGELOG.md

@@ -33,6 +33,7 @@
 - added config/fontconfig/45-Hack.conf for use on Linux distros to define Hack as a monospaced typeface
 - added ttdiff.sh shell script for OpenType table diffs of ttx XML dumps of font binaries
 - ttfautohint-build.sh, fixed backtick and expr syntax shellcheck warnings (SC2003/2006)
+- added checksum.py to scripts directory, supports the generation of SHA1 checksum files of font binaries and ttx dumps of OpenType tables
 - converted to Semaphore CI (from Travis CI) as CI testing service, eliminated .travis.yml settings file