Set utf-8 index.html character encoding

[nicolaichuk]

In browser js console error:

The character encoding of the HTML document was not declared. The document will render with garbled text in some browser configurations if the document contains characters from outside the US-ASCII range. The character encoding of the page must be declared in the document or in the transfer protocol.

Please add

<meta charset="utf-8">

in https://github.com/xpenatan/gdx-shadertoy/blob/master/dragome/webapp/index.html