[DOCS] Update Userguide (DNS) (#2987)

* update dns userguide docs

- add adguard
- add dns0
- remove Level3
- change google link from german to english

* remove unneeded negation

docs/userguide.md

@@ -77,13 +77,17 @@ The utility provides a convenient DNS selection feature, allowing users to choos
 
 * **Default**: Uses the default DNS settings configured by your ISP or network.
 * **DHCP**: Automatically acquires DNS settings from the DHCP server.
-* [**Google**](https://developers.google.com/speed/public-dns?hl=de): A reliable and fast DNS service provided by Google.
+* [**Google**](https://developers.google.com/speed/public-dns?hl=en): A reliable and fast DNS service provided by Google.
 * [**Cloudflare**](https://developers.cloudflare.com/1.1.1.1/): Known for speed and privacy, Cloudflare DNS is a popular choice for enhancing internet performance.
 * [**Cloudflare_Malware**](https://developers.cloudflare.com/1.1.1.1/setup/#:~:text=Use%20the%20following%20DNS%20resolvers%20to%20block%20malicious%20content%3A): Provides additional protection by blocking malware sites.
 * [**Cloudflare_Malware_Adult**](https://developers.cloudflare.com/1.1.1.1/setup/#:~:text=Use%20the%20following%20DNS%20resolvers%20to%20block%20malware%20and%20adult%20content%3A): Blocks both malware and adult content, offering more comprehensive filtering.
-* [**Level3**](https://www.lumen.com/): Another fast and reliable DNS service option.
 * [**Open_DNS**](https://www.opendns.com/setupguide/#familyshield): Offers customizable filtering and enhanced security features.
 * [**Quad9**](https://quad9.net/): Focuses on security by blocking known malicious domains.
+* [**AdGuard_Ads_Trackers**](https://adguard-dns.io/en/welcome.html) AdGuard DNS will block ads, trackers, or any other DNS requests. Visit website and login for a dashboard, statistics and customize your experience in the server settings.
+* [**AdGuard_Ads_Trackers_Malware_Adult**](https://adguard-dns.io/en/welcome.html) AdGuard DNS will block ads, trackers, adult content, and enable Safe Search and Safe Mode, where possible.
+* [**dns0.eu_Open**](https://www.dns0.eu/) The European public DNS that makes your Internet safer. Offers general-purpose filtering to block malware, phishing, and tracking domains for enhanced privacy and security.
+* [**dns0.eu_ZERO**](https://www.dns0.eu/zero) Provides advanced security with robust filters for highly sensitive environments, blocking high-risk domains using threat intelligence and sophisticated heuristics like Newly Registered Domains (NRD) and Domain Generation Algorithms (DGA).
+* [**dns0.eu_KIDS**](https://www.dns0.eu/kids) A child-safe DNS that blocks adult content, explicit search results, mature videos, dating sites, piracy, and ads, creating a secure internet experience for children on any device or network.
 
 ### Customize Preferences