Why a Release created from "User Story Map" directly going into Mainline on the "Feature -> Board" page.

When a user creates a "Release" from "User Story Map", the created "Release" will go at the left side (mainline) on "Feature -> Board" page (not in Parking Lot). While creating a Release user should have an option to select where he/she wants to create that Release in left side (mainline) or in Parking Lot (right side)