docs: note safeStorage.isEncryptionAvailable() needs ready event (#33739)

Co-authored-by: Shelley Vohr <[email protected]>

docs/api/safe-storage.md

@@ -20,7 +20,7 @@ Returns `boolean` - Whether encryption is available.
 
 On Linux, returns true if the secret key is
 available. On MacOS, returns true if Keychain is available.
-On Windows, returns true with no other preconditions.
+On Windows, returns true once the app has emitted the `ready` event.
 
 ### `safeStorage.encryptString(plainText)`