Add documentation for minirig/nonce range support.

FPGA-README

@@ -1,6 +1,18 @@
 
 This README contains extended details about FPGA mining with cgminer
 
+Bitforce
+
+--bfl-range         Use nonce range on bitforce devices if supported
+
+This option is only for bitforce devices. Earlier devices such as the single
+did not have any way of doing small amounts of work which meant that a lot of
+work could be lost across block changes. Some of the "minirigs" have support
+for doing this, so less work is lost across a longpoll. However, it comes at
+a cost of 1% in overall hashrate so this feature is disabled by default. It
+is only recommended you enable this if you are mining with a minirig on
+p2pool.
+
 
 Icarus
 

README

@@ -795,7 +795,9 @@ A; Try the --net-delay option.
 Q: How do I tune for p2pool?
 A: p2pool has very rapid expiration of work and new blocks, it is suggested you
 decrease intensity by 1 from your optimal value, and decrease GPU threads to 1
-with -g 1.
+with -g 1. It is also recommended to use --failover-only since the work is
+effectively like a different block chain. If mining with a minirig, it is worth
+adding the --bfl-range option.
 
 Q: Are kernels from other mining software useable in cgminer?
 A: No, the APIs are slightly different between the different software and they
@@ -812,6 +814,13 @@ They are Field-Programmable Gate Arrays that have been programmed to do Bitcoin
 mining. Since the acronym needs to be only 3 characters, the "Field-" part has
 been skipped.
 
+Q: How do I get my BFL device to auto-recognise?
+A: They are only automatically recognised on linux, and no option needs to be
+passed to them. The only thing that needs to be done is to load the driver for
+them, which on linux would require:
+sudo modprobe ftdi_sio vendor=0x0403 product=0x6014
+
+
 ---
 
 This code is provided entirely free of charge by the programmer in his spare