In the manual there is mention of the list: finder-known-keywords

   > File: elisp.info,  Node: Simple Packages,  Next: Multi-file Packages,  Prev: Packaging Basics,  Up: Packaging

   > 41.2 Simple Packages
   > ====================

   >    The ‘Keywords’ and ‘URL’ headers are optional, but recommended.  The
   > command ‘describe-package’ uses these to add links to its output.  The
   > ‘Keywords’ header should contain at least one standard keyword from the
   > ‘finder-known-keywords’ list.

   But I cannot find the list finder-known-keywords in Emacs

it is part of finder.el.