CH07: Use term "nested" for P2SH-P2WPKH/P2WSH

This is the phrasing used in BIP141.

chapters/authorization-authentication.adoc

@@ -1549,12 +1549,12 @@ Bob's wallet can then spend this payment with a segwit transaction,
 taking full advantage of segwit and reducing transaction fees.
 
 Both forms of witness scripts, P2WPKH and P2WSH, can be embedded in a
-P2SH address. The first is noted as P2SH(P2WPKH) and the second is noted
-as P2SH(P2WSH).
+P2SH address. The first is noted as nested P2WPKH and the second is noted
+as nested P2WSH.
 
-===== Pay-to-Witness-Public-Key-Hash inside Pay-to-Script-Hash
+===== Nested Pay-to-Witness-Public-Key-Hash
 
-The first form of witness script we will examine is P2SH(P2WPKH). This
+The first form of witness script we will examine is nested P2WPKH. This
 is a Pay-to-Witness-Public-Key-Hash witness program, embedded inside a
 Pay-to-Script-Hash script, so that it can be used by a wallet that is
 not aware of segwit.