webdoc rm link to pdf manual fragment

hugo/content/_index.md

@@ -18,10 +18,9 @@ Some features of the software are not yet documented.
 
 ## Other documents
 
-Complementary information can be found in the following documents:
+Complementary information can be found in the
 
 * Reference Paper: [J. Appl. Cryst. 2020]({{% url-paper %}})
-* [Physics Manual]({{% ref-manual %}}) (incomplete)
 
 Older course materials are at