Removing Notehub demo link

- Author states the website has been sold
https://github.com/chmllr/notehub/issues/58#issuecomment-404805693

README.md

@@ -1004,7 +1004,7 @@ See https://github.com/n1trux/awesome-sysadmin#monitoring and https://github.com
 - [hastebin](http://hastebin.com/about.md) - Open source pastebin written in node.js. ([Demo](http://hastebin.com/), [Source Code](https://github.com/seejohnrun/haste-server)) `MIT` `Nodejs`
 - [Modern Paste](https://www.modernpaste.com) - Modern pastebin with a contemporary, minimalistic user interface backed by a robust feature set. ([Demo](https://demo.modernpaste.com/), [Source Code](https://github.com/LINKIWI/modern-paste)) `MIT` `Python`
 - [mojopaste](http://search.cpan.org/dist/App-mojopaste/) - Perl based pastebin. ([Demo](http://p.thorsen.pm/), [Source Code](https://github.com/jhthorsen/app-mojopaste)) `Artistic-2.0` `Perl`
-- [NoteHub](https://notehub.org) - Free and Hassle-free Pastebin for Markdown Pages. Simple, clean, password provided, generated-short link. ([Demo](https://notehub.org), [Source Code](https://github.com/chmllr/NoteHub)) `MIT` `Nodejs`
+- [NoteHub](https://github.com/chmllr/NoteHub) - Free and Hassle-free Pastebin for Markdown Pages. Simple, clean, password provided, generated-short link. ([Source Code](https://github.com/chmllr/NoteHub)) `MIT` `Nodejs`
 - [Paste](https://phpaste.sourceforge.io/) - Paste is forked from the original source pastebin.com used before it was bought. ([Demo](https://phpaste.sourceforge.io/demo/), [Source Code](https://github.com/jordansamuel/PASTE)) `GPL-3.0` `PHP`
 - [pastebin](https://github.com/prologic/pastebin) - Simple pastebin service with convenient api and CLI. ([Demo](https://paste.mills.io)) `MIT` `Go`
 - [Pastebin](https://github.com/ewhal/Pastebin) - Modern self-hosted pastebin service with a restful API. `MIT` `Go`