Explain jumper settings

README.md

@@ -24,3 +24,41 @@ This board has been designed to bring the front FlexibleLOM mounting hole as
 close as possible to the PCIe bracket retention screw on a full size PCIe slot.
 You can use a small angled metal piece or a even a 3d printed one to mount the
 card into place.
+
+# Jumpers
+
+This adapter cards has several jumpers. You should not need to touch them, however
+the following sections will explain their purpose.
+
+## PERST
+
+This jumper selects where the PCIe reset signal is routed. By default it is routed
+to A1 on the FlexibleLOM slot. I believe this to be the PCIe reset signal. However,
+there is also another pin on the connector, A14 which behaves similarly to A1.  
+Testing has shown that the cards does not always enumerate properly when using A14
+as PCIe reset.  
+The two resistor footprints next to this jumper can be populated in case you are
+having issues with floating resets on the cards resulting in spurious resets. I
+have not encountered any such issues.
+
+## Vdet
+
+The Vdet jumper bridges +12V to pin B1 on the FlexibleLOM slot. I assume B1 to be
+some sort of voltage detection pin since it is routed very differently from all
+other +12V power signals on the card.
+
+## 3v3 aux
+
+The 3v3 aux jumper connects what I think is the auxiliary 3v3 volt voltage supply
+on the FlexibleLOM slot to the auxiliary 3v3 supply of the PCIe connector. Most
+cards I've seen do not use this voltage rail. However I assume there might be some
+that utilize it for WOL capability.
+
+## lanes
+
+This jumper controls which PRSNT2 pin is bridged to PRSNT1. It defaults to PRSNT2
+for 8x cards since that is the maximum number of lanes on a FlexibleLOM slot. You
+can try setting this jumper to 4x if you are having issues with card detection.  
+However, a lot of modern devices tend to ignore the PRSNT2 line and rely solely on
+detecting the lane transmitters/receivers. Thus this setting will be irrelevant for
+most devices.