Ideally you would create a new note with the content of the article. You should then go through and put double brackets around any important terms or concepts. Click on each of those new links so a new note is created for each term or concept. If you do this for multiple articles, each new note you create will begin to have a list of backlinks to each article that mentions that term/concept, acting like an index. You can even add your own thoughts about that term/concept on the note, expanding it's usefulness. I find this method of interlinking files to be very useful, resulting in a 'living index' of your vault.