Changes:
- The last section mentions "thresholds", while only a single threshold of 244 is specified in the bip. Clarify by changing to "threshold"
- Remove internal Bitcoin Core implementation detail. This is not relevant for a bip.
- Remove word "additional" when referring to safety buffer, since the safety buffer is the only buffer and not an additional one.
- Remove empty section "references"
- Add missing link to signaling implementation.