Add Dutch translation for Eclipse Collections website

[bmvermeer]

Already working on a Dutch translation of the website.

[nikhilnanivadekar]

@bmvermeer I made a few changes to remove some dated stuff from the website, so please take a look at the latest. The content is not changed but stuff like Latest News and the Javadoc versions are now reduced. I wanted to point it out to avoid any unnecessary confusion in the future 😄