Add a page for just a package (without version)

Ideally this gives us a stable URL that links to the latest version of the package. I was thinking about this because I wanted to make a badge that people could add to their READMEs that pointed to the page in the CHaP site for their package. But I want to link to just the `plutus-core` page, not the `plutus-core-0.1` page, which I would need to update every release.