DNS: add Nebulo as worth mentioning & warn about DoH metadata & sort worth mentioning/additional information into sublists (#1200)

* DNS: add Nebulo as worth mentioning

Resolves: #1187

* source_code: add Nebulo

* dns: add metadata warning to DoH

* dns: fix typo in Nebulo's description

Yes, Nebulo supports DoT and DoT...

* dns: update DoH warning text and link

* dns: sort mobile encrypted DNS software together

* dns: update DoH warning as suggested by @nitrohorse

* dns: sort additional information & worth mentioning into sublists

* dns: remove extra ul

* dns: sort the sublists

* dns: add formatting

* dns: update wording as requested by @nitrohorse

* dns: copy-paste @nitrohorse 's example

* source_code: sort DNS apps

* dns: swap Namecoin and Stubby due to alphabetical order

source_code.md

@@ -289,8 +289,6 @@ Webpage: https://github.com/opennic/opennic-web
 
 - NoTrack: https://github.com/quidsup/notrack
 
-- Namecoin: https://github.com/namecoin
-
 - Pi-hole: https://github.com/pi-hole
 
 ## Encrypted ICANN DNS Providers
@@ -305,10 +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