Update _config.yml
Update _config.yml

- Changed title to make the service (VPaaS) primary. Page title is also consistent with new page titles on corp site

- Changed description to be more precise. Took some language from home page.
kaltura/DeveloperPortalDocs,kaltura/DeveloperPortalDocs,kaltura/DeveloperPortalDocs,kaltura/DeveloperPortalDocs