Calibre does have their "book sharing" solution that are built in the software. However it is more like content server. Calibre-Web is a third-party solution that are not affiliated with Kovid Goyal (creator/main developer of calibre). And Calibre-Web is basically browser version of Calibre without requiring other people to use Calibre to access Calibre-Web. So Kovid did not create this calibre-web image from what I understand.