Add README file to FAA downloads directory.

docs/programmers/tutorials/workflows/downloads/topblast/README.rst

@@ -0,0 +1,11 @@
+.. Hey Emacs, this is -*- rst -*-
+
+   This file follows reStructuredText markup syntax; see
+   http://docutils.sf.net/rst.html for more information.
+
+
+The FAA files in this directory were downloaded from the online
+PATRIC_ database; meta-data and other information on the file content
+can be found there.
+
+.. _patric: https://www.patricbrc.org/portal/portal/patric/Home