Add a page for just a package (without version)

[michaelpj]

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.