source_code: sort DNS apps

source_code.md

@@ -285,14 +285,10 @@ OpenNic: https://github.com/opennic/ (mostly)
 
 Webpage: https://github.com/opennic/opennic-web
 
-Nebulo: https://git.frostnerd.com/PublicAndroidApps/smokescreen/
-
 ### Worth Mentioning
 
 - NoTrack: https://github.com/quidsup/notrack
 
-- Namecoin: https://github.com/namecoin
-
 - Pi-hole: https://github.com/pi-hole
 
 ## Encrypted ICANN DNS Providers
@@ -307,10 +303,18 @@ PowerDNS: https://github.com/PowerDNS/pdns
 
 ### Worth Mentioning and Additional Information
 
+#### Mobile
+
 - DNSCloak: https://github.com/s-s/dnscloak
 
+- Nebulo: https://git.frostnerd.com/PublicAndroidApps/smokescreen/
+
+#### Local DNS servers
+
 - Stubby: https://github.com/getdnsapi/stubby
 
+- Namecoin: https://github.com/namecoin
+
 ## Digital Notebook
  Joplin: https://github.com/laurent22/joplin