Merge #16239: wallet/rpc: follow-up clean-up/fixes to avoid_reuse

71d0344cf2 docs: release note wording (Karl-Johan Alm)
3d2ff37913 wallet/rpc: use static help text (Karl-Johan Alm)
53c3c1ea9e wallet/rpc/getbalances: add entry for 'mine.used' balance in results (Karl-Johan Alm)

Pull request description:

  This addresses a few remaining issues pointed out in #13756:

  * First commit addresses https://github.com/bitcoin/bitcoin/pull/13756#discussion_r284907468
  * Second commit addresses https://github.com/bitcoin/bitcoin/pull/13756#discussion_r294868973

  Ping jnewbery and achow101 as they pointed out these issues.

ACKs for commit 71d034:
  jnewbery:
    ACK 71d0344cf2
  meshcollider:
    re-utACK 71d0344cf2

Tree-SHA512: 5e28822af0574ad07dbbed21aa2fe7866bf5770b4c0a1c150ad0da8af3152bcfb7170330a7497fa500326c594740ecf63733cf58325821e2811d7b911d5783a0

doc/release-notes-13756.md

@@ -7,8 +7,8 @@ A new wallet flag `avoid_reuse` has been added (default off). When enabled,
 a wallet will distinguish between used and unused addresses, and default to not
 use the former in coin selection.
 
-(Note: rescanning the blockchain is required, to correctly mark previously
-used destinations.)
+Rescanning the blockchain is required, to correctly mark previously
+used destinations.
 
 Together with "avoid partial spends" (present as of Bitcoin v0.17), this
 addresses a serious privacy issue where a malicious user can track spends by
@@ -30,10 +30,12 @@ These include:
 
 - createwallet
 - getbalance
+- getbalances
 - sendtoaddress
 
-In addition, `sendtoaddress` has been changed to enable `-avoidpartialspends` when
-`avoid_reuse` is enabled.
+In addition, `sendtoaddress` has been changed to avoid partial spends when `avoid_reuse`
+is enabled (if not already enabled via the  `-avoidpartialspends` command line flag),
+as it would otherwise risk using up the "wrong" UTXO for an address reuse case.
 
 The listunspent RPC has also been updated to now include a "reused" bool, for nodes
 with "avoid_reuse" enabled.