specs: typo - should be 'responsibility'

specs/derivation.md

@@ -88,7 +88,7 @@
 > **Note** the following assumes a single sequencer and batcher. In the future, the design will be adapted to
 > accomodate multiple such entities.
 
-[L2 chain derivation][g-derivation] — deriving L2 [blocks][g-block] from L1 data — is one of the main responsability of
+[L2 chain derivation][g-derivation] — deriving L2 [blocks][g-block] from L1 data — is one of the main responsibility of
 the [rollup node][g-rollup-node], both in validator mode, and in sequencer mode (where derivation acts as a sanity check
 on sequencing, and enables detecting L1 chain [re-organizations][g-reorg]).