Merge branch 'sb/pack-protocol-doc-nak' into maint

A doc update.

* sb/pack-protocol-doc-nak:
  Documentation: pack-protocol correct NAK response

Author: gitster

Documentation/technical/pack-protocol.txt

@@ -307,7 +307,7 @@ In multi_ack mode:
     ready to make a packfile, it will blindly ACK all 'have' obj-ids
     back to the client.
 
-  * the server will then send a 'NACK' and then wait for another response
+  * the server will then send a 'NAK' and then wait for another response
     from the client - either a 'done' or another list of 'have' lines.
 
 In multi_ack_detailed mode: