Update USAGE.md file

Signed-off-by: Kalyan <kalyan.menda@whiteskylabs.com>
removed Custome aggregator flow file

Signed-off-by: Kalyan <kalyan.menda@whiteskylabs.com>
Updated component display names in mule flows

Signed-off-by: Kalyan <kalyan.menda@whiteskylabs.com>
Updated Usage.md