Update images in docs/authentication/authentication.rst in branch 5.2

Description

The user interface in docs/authentication/authentication.rst has changed, and the images in this documentation need to be updated to reflect the new UI.

Website page

https://docs.mautic.org/en/5.2/authentication/authentication.html

Suggestions

The following images are referenced and need to be reviewed and updated as needed:

• docs/authentication/images/turn-on-saml.png
• docs/authentication/images/roles-permissions.png
• docs/authentication/images/authentication-settings.png

Important notes

• Please follow the instructions on the website page to navigate Mautic.
• Please use the light mode to take the screenshots.
• Please zoom out bit by bit until you can capture the whole component if the component occupied the screen or need to be scrolled.
• Please use red color if you need to highlight (create a box for) the components.
• Please save the images in .png.
• Always test and preview your changes locally to ensure that the images are rendered properly.

Open docs/authentication/authentication.rst and review the linked 5.2 website page, then navigate Mautic in light mode to compare the referenced screenshots. Update turn-on-saml.png, roles-permissions.png, and authentication-settings.png as needed, save them as PNGs, and preview the documentation locally to confirm the images render correctly.