Fix broken links in README.md , in particular for installation (!201) · Merge requests · European Space Agency / Pyxel · GitLab

Hugo Buddelmeijer requested to merge hugobuddel/pyxel:hugobuddel-master-patch-77647 into master Apr 21, 2021

Fixes broken links in README.md , in particular for installation

Both of these were 'here' links which have been replaced, as well as a third, see https://webaccess.berkeley.edu/ask-pecan/click-here