Update glossary.asciidoc

Corrected difficulty retarget interval.

glossary.asciidoc

@@ -28,7 +28,7 @@ difficulty target::
  	A difficulty at which all the computation in the network will find blocks approximately every 10 minutes.((("target difficulty")))
 
 difficulty retargeting::
-	A network-wide recalculation of the difficulty that occurs once every 2,106 blocks and considers the hashing power of the previous 2,106 blocks.((("difficulty retargeting")))
+	A network-wide recalculation of the difficulty that occurs once every 2,016 blocks and considers the hashing power of the previous 2,016 blocks.((("difficulty retargeting")))
 	
 fees::
 	The sender of a transaction often includes a fee to the network for processing the requested transaction.  Most transactions require a minimum fee of 0.5 mBTC.((("fees")))
@@ -58,4 +58,4 @@ transaction::
 In simple terms, a transfer of bitcoins from one address to another. More precisely, a transaction is a signed data structure expressing a transfer of value. Transactions are transmitted over the bitcoin network, collected by miners, and included into blocks, made permanent on the blockchain.((("transaction")))
 
 wallet::
-Software that holds all your bitcoin addresses and secret keys. Use it to send, receive, and store your bitcoin.((("wallet"))) 
+Software that holds all your bitcoin addresses and secret keys. Use it to send, receive, and store your bitcoin.((("wallet")))