Update repo to reflect rebrand to Magical

The chrome devstore link looks to be rebranded as "Magical – Text Expansion" now - https://chrome.google.com/webstore/detail/magical-%E2%80%93-text-expansion/iibninhmiggehlcdolcilmhacighjamp, further linking to https://www.getmagical.com/

Could this repo be updated with the new branding & current code release?