2018-06-21 meeting: add some additional content

- Describe implications of loadwallet not automatically persisting
  across restarts
- Add extended pubkeys to list of key material bech32x is being designed
  for

Both suggested by John Newbery.  Thanks!

Author: harding

_posts/en/meetings/2018-06-21-meeting.md

@@ -184,7 +184,11 @@ separately.
 **Discussion ([log][log multiwallet persistence]):** Jonas Schnelli
 requested and introduced the topic, "I guess it's not ideal that loaded
 wallets need to be re-loaded after a Bitcoin Core restart---especially
-in pruning mode."
+in pruning mode."  That is, a user who creates or loads a wallet and
+then restarts Bitcoin Core without changing the configuration file will
+have to rescan the latest parts of the block chain the next time they do
+load that wallet.  Worse, if some of the blocks the rescan needs have
+been pruned, the user will be unable to use the wallet.
 
 Several meeting participants suggested that this is what the
 writable Bitcoin config file (rwconf) is being developed for.  See PR
@@ -201,7 +205,8 @@ Schnelli.
 
 **Background:** several Bitcoin Core contributors have been working to
 create a new serialization format for backing up and recovering Bitcoin
-private keys, HD-wallet seeds, and HD-wallet extended private keys.  The
+private keys, HD-wallet seeds, HD-wallet extended private keys, and
+HD-wallet extended public keys.  The
 primary goal is to replace the current popular standards of base58check
 and BIP39 with a new standard that not only detects errors but can also
 automatically correct several of those errors for the user.  Current