China’s manufacturing contracted in April for the fourth straight month but the pace of decline was less severe, suggesting the downturn in the world’s No. 2 economy is bottoming out. HSBC’s purchasing managers’ index released Monday ticked up to 48.1 from 48.0 in March on a 100-point scale on which numbers above 50 indicate expansion. The reading is slightly lower than 48.3 in a preliminary version of the report last month. But it’s the first time the index has risen since it started falling from 50.9 in October