Add limitations and constraints

Makefile

@@ -122,6 +122,7 @@ DISABLE_STANDARD_WEBUSB = 1
 DEFINES   += CUSTOM_IO_APDU_BUFFER_SIZE=\(255+5+64\)
 DEFINES   += HAVE_USB_CLASS_CCID
 DEFINES   += HAVE_RSA
+# Watchdog issue causing the device reset with long prime number computation
 # DEFINES   += WITH_SUPPORT_RSA4096
 
 ifeq ($(TARGET_NAME),TARGET_NANOS)

README.md

@@ -321,3 +321,11 @@ It outputs 3 artifacts:
 
 - `compiled_app_binaries` within binary files of the build process for each device
 - `code-coverage` within HTML details of code coverage
+
+## Known limitations
+
+Today, the current App has some known limitations.
+
+- RSA4096 is disabled, because of an issue with the watchdog, resetting the device
+  during long prime number operation.
+- Using Ed25519 template, the decrypt doesn't output a correct result.