Update Prerequisites.md

Added info about USB Dongle sizes/form factors.

Author: qqubes

Installing-and-Configuring/Prerequisites.md

@@ -60,6 +60,9 @@ USB Security Dongles (aka security token aka smartcard)
 
  *NOTE* - HOTP remote attestation is supported from Librem platforms by default, 
   Otherwise HOTP is explicitely supported by board configurations having `hotp` in their [board names](/Prerequisites#supported-devices).
+  
+*NOTE* - The NitroKey 3 comes in three sizes: USB A, A-mini and C. Nk3a mini (USB A-mini) is the one most shipped with novacustom and nitropads.
+  - ThinkPads have USB A ports, not C. After that, it's users preferences for the form factor desired. 
 
 |Manufacture|Model line|TOTP|HOTP|
 |--|--|:--:|:--:|