Update doc.go

Fix typo.

Author: nadimkobeissi

ecc/bls12381/doc.go

@@ -1,6 +1,6 @@
 // Package bls12381 provides bilinear pairings using the BLS12-381 curve.
 //
-// A pairing system consists of three groups G1 and G2 (adiitive notation) and
+// A pairing system consists of three groups G1 and G2 (additive notation) and
 // Gt (multiplicative notation) of the same order.
 // Scalars can be used interchangeably between groups.
 //