Update CREDITS.md
Update CREDITS.md

Add all new authors (extracted with the following command):
git log --format="%aN" dec91e7aa0f2750fbdf98e7244cfca88ca3b9719..HEAD | sort /unique
GerHobbelt/civet-webserver,GerHobbelt/civet-webserver,GerHobbelt/civet-webserver,GerHobbelt/civet-webserver,GerHobbelt/civet-webserver,GerHobbelt/civet-webserver