doc: clarify that BDB is only required for the legacy wallet

Author: fanquake

doc/build-unix.md

@@ -209,7 +209,7 @@ from the root of the repository.
 
 Otherwise, you can build Bitcoin Core from self-compiled [depends](/depends/README.md).
 
-**Note**: You only need Berkeley DB if the wallet is enabled (see [*Disable-wallet mode*](#disable-wallet-mode)).
+**Note**: You only need Berkeley DB if the legacy wallet is enabled (see [*Disable-wallet mode*](#disable-wallet-mode)).
 
 Security
 --------
@@ -259,12 +259,12 @@ Hardening enables the following features:
 
 Disable-wallet mode
 --------------------
-When the intention is to run only a P2P node without a wallet, Bitcoin Core may be compiled in
-disable-wallet mode with:
+When the intention is to only run a P2P node, without a wallet, Bitcoin Core can
+be compiled in disable-wallet mode with:
 
     ./configure --disable-wallet
 
-In this case there is no dependency on Berkeley DB 4.8 and SQLite.
+In this case there is no dependency on SQLite or Berkeley DB.
 
 Mining is also possible in disable-wallet mode using the `getblocktemplate` RPC call.