Feat: lighthouse book - ui authentication (#4232)

## Proposed Changes

Added page explanation for authentication under Siren UI book.

## Additional Info

Please provide any additional information. For example, future considerations
or information useful for reviewers.

book/src/ui-authentication.md

@@ -0,0 +1,33 @@
+# Authentication
+
+To enhance the security of your account, we offer the option to set a session password. This allows the user to avoid re-entering the api-token when performing critical mutating operations on the validator. Instead a user can simply enter their session password. In the absence of a session password, Siren will revert to the api-token specified in your configuration settings as the default security measure.
+
+> This does not protect your validators from unauthorized device access. 
+
+![](imgs/ui-session-auth.png)
+
+Session passwords must contain at least:
+
+- 12 characters
+- 1 lowercase letter
+- 1 uppercase letter
+- 1 number
+- 1 special character
+
+
+## Protected Actions
+
+Prior to executing any sensitive validator action, Siren will request authentication of the session password or api-token.
+
+![](imgs/ui-exit.png)
+
+
+In the event of three consecutive failed attempts, Siren will initiate a security measure by locking all actions and prompting for configuration settings to be renewed to regain access to these features.
+
+![](imgs/ui-fail-auth.png)
+
+## Auto Connect
+
+In the event that auto-connect is enabled, refreshing the Siren application will result in a prompt to authenticate the session password or api-token. If three consecutive authentication attempts fail, Siren will activate a security measure by locking the session and prompting for configuration settings to be reset to regain access.
+
+![](imgs/ui-autoconnect-auth.png)