Update Windows build to sqlite 3.6.21.
diff --git a/PCbuild/readme.txt b/PCbuild/readme.txt
index 44b7b8f..0386b45 100644
--- a/PCbuild/readme.txt
+++ b/PCbuild/readme.txt
@@ -107,7 +107,7 @@
     Wraps Berkeley DB 4.7.25, which is currently built by _bsddb.vcproj.
     project (see below).
 _sqlite3
-    Wraps SQLite 3.5.9, which is currently built by sqlite3.vcproj (see below).
+    Wraps SQLite 3.6.21, which is currently built by sqlite3.vcproj (see below).
 _tkinter
     Wraps the Tk windowing system.  Unlike _bsddb and _sqlite3, there's no
     corresponding tcltk.vcproj-type project that builds Tcl/Tk from vcproj's