Document that we dropped support for OpenSSL 0.9.8 (#521)

diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index 0fc4572..8afa448 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -40,7 +40,7 @@
 Deprecations:
 ^^^^^^^^^^^^^
 
-*none*
+- Dropped support for OpenSSL 0.9.8.
 
 
 Changes: