**Describe the bug** Configuring heading levels in blockSpecs while creating BlockNoteSchema has no effect. **To Reproduce** Link t reproducible example https://stackblitz.com/github/TypeCellOS/BlockNote/tree/main/examples/06-custom-schema/07-configuring-blocks?file=src%2FApp.tsx Taken from official example. Link: https://www.blocknotejs.org/examples/custom-schema/configuring-blocks