Add Ziggurat Exponential generator to CHANGES.md
Add Ziggurat Exponential generator to CHANGES.md

kevinmeredith/spire,tixxit/spire,kevinmeredith/spire,non/spire,tixxit/spire,codeaudit/spire,adampingel/spire,guersam/spire,siddhartha-gadgil/spire,AlecZorab/spire,guersam/spire,siddhartha-gadgil/spire,rklaehn/spire,adampingel/spire,woparry/spire,non/spire,AlecZorab/spire,rklaehn/spire,woparry/spire,codeaudit/spire,JackSullivan/spire,JackSullivan/spire