Update API references in Makefile and README.md to fix rebranding issue from polygon.io to massive.com#960

justinpolygon merged 1 commit into

massive-com:mastermassive-com/client-python:masterfrom

aaronspindler:fix-links-to-incorrect-urlaaronspindler/client-python:fix-links-to-incorrect-urlCopy head branch name to clipboard