docs: Add PySide installation instructions
docs: Add PySide installation instructions

adongy/spreads,adongy/spreads,gareth8118/spreads,jbaiter/spreads,jbaiter/spreads,miloh/spreads,gareth8118/spreads,nafraf/spreads,gareth8118/spreads,jbaiter/spreads,adongy/spreads,DIYBookScanner/spreads,miloh/spreads,nafraf/spreads,nafraf/spreads,miloh/spreads,DIYBookScanner/spreads,DIYBookScanner/spreads