Clarify definition of Page and Version

ARCHITECTURE.md

@@ -6,9 +6,9 @@
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 ## Definition of Terms
 
-* **Page**: a web page crawled over time by one or more services like the Internet
+* **Page**: a web resource (HTML pages, PDFs, Excel spreadsheets, CSVs, images, etc.) crawled over time by one or more services like the Internet
   Archive or Versionista.
-* **Version**: a snapshot of a Page at a specific time (saved as HTML, for now).
+* **Version**: a snapshot of a Page at a specific time that is different from a previous Version. 
 * **Change**: two different Versions of the same Page.
 * **Diff**: a representation of a Change: this could be a plain text `diff` (as in
   the UNIX command line utility) or a richer representation such as differences in the rendered HTML.
@@ -17,8 +17,6 @@
   be annotated by multiple analysts, thus creating multiple Annotations per
   Change.
 
-For more detail, see the Schema section below.
-
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 ## System Architecture