openssl 1.1.1 testing (#4112)

* test openssl 1.1.1

* let's see what a 1.1.1 pyopenssl does

* 1.1.1-pre8

* pre9

* docs and test more things

* 3.7 needs xenial
diff --git a/docs/installation.rst b/docs/installation.rst
index a4649f5..d665dbc 100644
--- a/docs/installation.rst
+++ b/docs/installation.rst
@@ -28,6 +28,7 @@
 * ``OpenSSL 1.0.1f``
 * ``OpenSSL 1.0.2-latest``
 * ``OpenSSL 1.1.0-latest``
+* ``OpenSSL 1.1.1-latest``
 
 Building cryptography on Windows
 --------------------------------