(core/23-commitment/types) doc: fix typo (cosmos#1694)

Author: renaynay

modules/core/23-commitment/types/merkle.go

@@ -128,7 +128,7 @@ func ApplyPrefix(prefix exported.Prefix, path MerklePath) (MerklePath, error) {
 
 var _ exported.Proof = (*MerkleProof)(nil)
 
-// VerifyMembership verifies the membership pf a merkle proof against the given root, path, and value.
+// VerifyMembership verifies the membership of a merkle proof against the given root, path, and value.
 func (proof MerkleProof) VerifyMembership(specs []*ics23.ProofSpec, root exported.Root, path exported.Path, value []byte) error {
 	if err := proof.validateVerificationArgs(specs, root); err != nil {
 		return err