fix(explorer): correct URL for preview explorers
fix(explorer): correct URL for preview explorers

owid/owid-grapher,OurWorldInData/owid-grapher,OurWorldInData/owid-grapher,owid/owid-grapher,owid/owid-grapher,owid/owid-grapher,owid/owid-grapher,OurWorldInData/owid-grapher,OurWorldInData/owid-grapher,OurWorldInData/owid-grapher