Add a changelog with some entries

ChangeLog.rst

+Changelog for tahoe-ssk
+=======================
+
+0.2.0.0
+-------
+
+* Add the IV as a parameter to Tahoe.SDMF.encode.
+  The IV must be the value used to create the ciphertext so Tahoe.SDMF.encode cannot randomly generate one.
+* Add Tahoe.SDMF.randomIV for randomly generating a new IV.
+
+0.1.0.0
+-------
+
+* Initial release.
+* Very basic non-verifying decoding support.
+* Enough encoding support for simple round-trip tests for the decoding functionality.

tahoe-ssk.cabal

@@ -54,8 +54,11 @@ build-type:         Simple
 extra-doc-files:    CHANGELOG.md
 
 -- Extra source files to be distributed with the package, such as examples, or
--- a tutorial module.  In our case, test data.
+-- a tutorial module.
+extra-source-files:
+  ChangeLog.rst
+  README.rst
+  test/data/*
 
 common warnings
   ghc-options: -Wall -Werror=missing-fields