Add self-contained PDF edition and link it from the landing page

Author: Peter Wang

index.md

@@ -22,6 +22,10 @@ essay's argument as a spoken piece.
 [**essay**](the-unmoored-self.md) (~6,000 words). It is the authoritative
 version; everything else derives from it.
 
+**If you prefer one file:** the
+[**self-contained PDF**](unmoored-self.pdf) (60 pages) collects the essay,
+the briefing suite, the audio mini-book, and the sources index.
+
 ## The briefing suite
 
 For teams building community and social software — the diagnosis in