CH01::Addresses: mention invoices also; mention privacy concerns about address sharing

- The previous text only refers to onchain addresses, but BIP22 URIs,
  QR-encoded BIP22 URIs, and offchain invoices (like BOLT11) are the way
  many users will now exchange payment information, so the tipbox is
  generalized to refer to both addresses and invoices.

- A few words are added to clarify why sharing an address or invoice
  doesn't create security risks: Bitcoin is push-only.

- We mention the privacy downsides of sharing addresses or invoices and
  encourage generating new addresses for each payment.

ch01.asciidoc

@@ -409,17 +409,19 @@ Alice is now ready to start using her new bitcoin wallet. ((("", startref="GSqui
 
 [TIP]
 ====
-((("addresses", "security of")))((("security", "bitcoin
-addresses")))Bitcoin addresses start with a 1 or 3. Like email
-addresses, they can be shared with other bitcoin users who can use them
-to send bitcoin directly to your wallet. There is nothing sensitive,
-from a security perspective, about the bitcoin address. It can be posted
-anywhere without risking the security of the account. Unlike email
-addresses, you can create new addresses as often as you like, all of
-which will direct funds to your wallet. In fact, many modern wallets
-automatically create a new address for every transaction to maximize
-privacy. A wallet is simply a collection of addresses and the keys that
-unlock the funds within.
+((("addresses", "security of")))((("security", "bitcoin addresses")))There
+are a variety of Bitcoin addresses and formats for sharing Bitcoin
+invoices.  Addresses and invoices can be shared with other bitcoin users
+who can use them to send bitcoin directly to your wallet.  You can share
+an address or invoice with other people without worrying about the
+security of your bitcoins.  Unlike a bank account number, nobody who
+learns one of your Bitcoin addresses can withdraw money from your wallet--you
+must initiate all spends.  However, if you give two people the same
+address, they will be able to see how much bitcoin the other person sent
+you.  If you post your address publicly, everyone will be able to see
+how much bitcoin other people sent you.  To protect your privacy, you
+should generate a new invoice with a new address each time you request a
+payment.
 ====
 
 In most wallets, there is no association between a Bitcoin address and any externally identifiable information including the user's identity. Until the moment an address is referenced as the recipient of value in a transaction posted on the bitcoin ledger, the Bitcoin address is simply part of the vast number of possible addresses that are valid in bitcoin. Only once an address has been associated with a transaction does it become part of the known addresses in the network.