Document the v2 encryption feature flags

.env.template

@@ -410,6 +410,12 @@
 ## - "biometrics-sdk-ipc": Enable biometric unlock over the SDK IPC framework (Desktop >= 2026.9.0, Browser >= 2026.9.0)
 ## - "windows-native-credential-sync": Register the desktop app as a passkey provider in Windows, so passkeys in the vault can be used by other apps and browsers.
 ##   Requires the Microsoft Store (appx) build of the desktop app. Stable releases up to and including 2026.9.1 lack the required plugin registration, so it has no effect there yet.
+## - "pm-27278-v2-password-registration": Register new accounts with v2 encryption. (Web >= 2026.6.4, Desktop/Browser/CLI >= 2026.7.0, Android >= 2026.4.1, iOS >= 2026.5.1)
+## - "enable-account-encryption-v2-jit-password-registration": Give SSO users who set their master password on their first login v2 encryption. (Web >= 2026.1.1, Desktop/Browser/CLI >= 2026.1.0, Android >= 2026.4.1, iOS >= 2026.6.0)
+## - "force-upgrade-v2-encryption": Upgrade every v1 account to v2 encryption the next time it's unlocked in a web, desktop, browser or CLI client. (Web >= 2026.6.4, Desktop/Browser/CLI >= 2026.7.0)
+##   These three flags can't be undone: a v2 account stays v2, and it can only log in from clients that are 2025.11.0 or newer and send their version, which rules out some older and third-party clients.
+## - "pm-30144-sdk-key-rotation": Only for clients up to 2026.10.0 (Desktop up to 2026.10.1): together with "force-upgrade-v2-encryption", a manual key rotation also upgrades a v1 account to v2.
+## - "pm-31050-no-logout-key-upgrade-rotation": Only for clients 2026.6.0 to 2026.10.0 (Desktop up to 2026.10.1): sync instead of logging out after the upgrade to v2. Newer clients always do.
 # EXPERIMENTAL_CLIENT_FEATURE_FLAGS=
 
 ## Require new device emails. When a user logs in an email is required to be sent.