settings: revert default indentUnit to 4
settings: revert default indentUnit to 4

since 4 is more common than 3 in other editors

brunosxs/laverna,Laverna/laverna,brunosxs/laverna,JerJohn15/laverna,Laverna/laverna,JerJohn15/laverna,xeddmc/laverna,xeddmc/laverna