Implemented 3 more language options for the Plugin

[GScripter]

Hello 👋. Users from all over the world use Vim and although English is kind of a norm in the development world, many people are still not familiar with the language, so they end up not understanding the messages generated by Vim-Startify, so it becomes just another meaningless random text, I thought about it and decided to bring this update to the code, where the user, through the definition of a variable in the .vimrc, has the option to choose between 3 languages, Portuguese, Spanish and Chinese, in case the variable does not is set, English will be used by default. There is certainly no way to translate into all existing languages, but only with these it is already possible to have a wide range.

let g:startify_language = 'pt-br' # Portuguese
let g:startify_language = 'es' # Spanish
let g:startify_language = 'ch' # Chinese