Move cryptography.vectors to cryptography_vectors

All vectors are now stored in the subpackage in the vectors/ folder.

This package is automatically installed by setup.py test and will also
be uploaded with a matching version number by the PyPI upload task.
diff --git a/docs/development/test-vectors.rst b/docs/development/test-vectors.rst
index 164d0ab..c5ea815 100644
--- a/docs/development/test-vectors.rst
+++ b/docs/development/test-vectors.rst
@@ -2,10 +2,14 @@
 ============
 
 Testing the correctness of the primitives implemented in each ``cryptography``
-backend requires trusted test vectors. Where possible these vectors are obtained
-from official sources such as `NIST`_ or `IETF`_ RFCs. When this is not possible
-``cryptography`` has chosen to create a set of custom vectors using an official
-vector file as input to verify consistency between implemented backends.
+backend requires trusted test vectors. Where possible these vectors are
+obtained from official sources such as `NIST`_ or `IETF`_ RFCs. When this is
+not possible ``cryptography`` has chosen to create a set of custom vectors
+using an official vector file as input to verify consistency between
+implemented backends.
+
+Vectors are kept in the `cryptography_vectors` package rather than within our
+main test suite.
 
 Sources
 -------
diff --git a/docs/doing-a-release.rst b/docs/doing-a-release.rst
index 8b37df7..fc88a91 100644
--- a/docs/doing-a-release.rst
+++ b/docs/doing-a-release.rst
@@ -10,6 +10,7 @@
 software.
 
 * Update the version number in ``cryptography/__about__.py``.
+* Update the version number in ``vectors/cryptography_vectors/__about__.py``.
 * Set the release date in the :doc:`/changelog`.
 * Do a commit indicating this.
 * Send a pull request with this.
@@ -33,5 +34,8 @@
     >>> import cryptography
     >>> cryptography.__version__
     '...'
+    >>> import cryptography_vectors
+    >>> cryptography_vectors.__version__
+    '...'
 
 Verify that this is the version you just released.