Update demo.vue

[vitheeshc]

maxFilesize changed to 30 mb

[Chomiciak]

This very much depends.
Bare in mind, this package will be used in various scenarios, including multiple different servers, technologies and such.
For the sake of properly guiding beginners, we should keep the limit somewhere safe under their server's limit, that is, default e.g.: 2MB for apache, 1MB for nginx, etc.

Why? Because in the process of learning, limitations they overcome should be gradual.
And they will copy-paste this code to check if it works in their environment, so ideally it should work as-is to make adjustments easier.

I would suggest to change the docs first, mention the problem and possible solutions, then think about rising the limit in our code.