readme: update info re: modern key support

README.md

@@ -5,14 +5,6 @@ creating and installing SSL certificates on APC (Schneider Electric)
 Network Management Cards (2 & 3) simple and easy to do. It is also 
 designed to simplify automation of the certificate management lifecycle.
 
-## Help Needed from NMC3 Users!
-
-If you have an NMC3, please test the beta release (1.1.0-b). In particular,
-please provide feedback if 4,092 bit RSA keys and EC keys of curve types
-P-256, P-384, and P-521 work using the beta and your NMC3.
-
-see: https://github.com/gregtwallace/apc-p15-tool/issues/6
-
 ## Background
 
 When APC created the NMC2 (Network Management Card 2), they chose to use 
@@ -71,12 +63,17 @@ NMC2 device in a home lab and have no way to guarantee success in all cases.
 NMC2:
 - RSA 1,024, 2,048, 3,072* bit lengths.
 
-NMC3:
+NMC3*:
 - RSA 1,024, 2,048, 3,072, and 4,092 bit lengths.
 - ECDSA curves P-256, P-384, and P-521. 
 
 * 3,072 bit length is not officially supported by my NMC2, but appears to work
   fine.
+* The additional key types supported by NMC3 require newer firmware on the
+  device. I am unsure what the version cutoff is, but you can check support
+  by connecting to the UPS via SSH and typing `ssl`. If `Command Not Found`
+  is returned, the firmware is too old and only the key types listed under
+  NMC2 will work.
 
 1,024 bit RSA is no longer considered completely secure; avoid keys of 
 this size if possible. Most (all?) public ACME services won't accept keys