Added VAT number for GitLab BV
The VAT number is needed by EU based contractors, may as well have it on the website. This site (in Dutch) by the belastingdienst points out that the EU requires that the VAT number be made quite freely available, but it is up to companies individually to figure out what that means... putting it online is an option. My assumption is therefore that this does not pose a significant security threat.
\cc @pmachle1 @wilsonlau