Update README.md

Hi *Wikia development community*, :smile: 

The **forum website** *"http://www.mwusers.com"* don't exist! :unamused: 
Because the website was redirect to an ad website!!!

So I correct the *README.md* file at the bottom. :pencil: 

Yours,
[**Suriyaa Kudo**](https://github.com/SuriyaaKudoIsc) :octocat: