docs: secure-boot-v2: remove incorrect note about bootloader re-flash

In secure-boot-v2 scheme, one can always regenerate signature using
secure boot signing key and re-flash either bootloader or application.

docs/en/security/secure-boot-v2.rst

@@ -289,7 +289,7 @@ How To Enable Secure Boot V2
 
     4. Select the desired UART ROM download mode in "UART ROM download mode". By default, it is set to "Permanently switch to Secure mode" which is generally recommended. For production devices, the most secure option is to set it to "Permanently disabled".
 
-5. Set other menuconfig options (as desired). Pay particular attention to the "Bootloader Config" options, as you can only flash the bootloader once. Then exit menuconfig and save your configuration.
+5. Set other menuconfig options (as desired). Then exit menuconfig and save your configuration.
 
 6. The first time you run ``idf.py build``, if the signing key is not found then an error message will be printed with a command to generate a signing key via ``espsecure.py generate_signing_key``.