Fix some typos.

README.rst

@@ -83,9 +83,10 @@ The above are in no particular order.
 Database Format
 ===============
 
-The database and metadata formats of ElectrumX is certain to change in
+The database and metadata formats of ElectrumX are certain to change
-the future which will render old DBs unusable.  For now I do not
+in the future.  Such a change will render old DBs unusable.  For now I
-intend to provide converters as the rate of flux is high.
+do not intend to provide converters as this is still non-production
+software.  Moreover from-genesis sync time is quite bearable.
 
 
 Miscellany

samples/scripts/NOTES

@@ -24,19 +24,20 @@ REORG_LIMIT   - maximum number of blocks to be able to handle in a chain
                 Default is 200.
 TCP_PORT      - if set will serve Electrum clients on that port
 SSL_PORT      - if set will serve Electrum clients over SSL on that port.
-                If set SSL_CERTFILE and SSL_KEYFILE must be filesystem paths
+                If set, SSL_CERTFILE and SSL_KEYFILE must be filesystem paths.
 RPC_PORT      - Listen on this port for local RPC connections, defaults to
                 8000.
 BANNER_FILE   - a path to a banner file to serve to clients.  The banner file
                 is re-read for each new client.
 DONATION_ADDRESS  - server donation address.  Defaults to none.
 
-Your performance might change by tweaking these cache settings.  Cache
+Your performance might change by tweaking the following cache
-size is only checked roughly every minute, so the caches can grow
+variables.  Cache size is only checked roughly every minute, so the
-beyond the specified size.  Also the Python process is often quite a
+caches can grow beyond the specified size.  Also the Python process is
-bit bigger than the combine cache size, because of Python overhead and
+often quite a bit fatter than the combined cache size, because of
-also because leveldb can consume quite a lot of memory during UTXO
+Python overhead and also because leveldb consumes a lot of memory
-flushing.  So these are rough numbers only:
+during UTXO flushing.  So I recommend you set the sum of these to
+nothing over half your available physical RAM:
 
 HIST_MB   - amount of history cache, in MB, to retain before flushing to
             disk.  Default is 250; probably no benefit being much larger

server/block_processor.py

@@ -734,7 +734,6 @@ class BlockProcessor(LoggedClass):
         limit = self.resolve_limit(limit)
         unpack = struct.unpack
         prefix = b'u' + hash168
-        utxos = []
         for k, v in self.db.iterator(prefix=prefix):
             (tx_pos,) = unpack('<H', k[-2:])