Fixes #4426 -- use modern idiom in our bindings docs (#4428)

diff --git a/docs/development/c-bindings.rst b/docs/development/c-bindings.rst
index 8a9bb6d..1b58dab 100644
--- a/docs/development/c-bindings.rst
+++ b/docs/development/c-bindings.rst
@@ -191,7 +191,7 @@
 one. In that case, it may make sense to either check for a particular
 version. For example, to check for OpenSSL 1.1.0 or newer::
 
-    #if OPENSSL_VERSION_NUMBER >= 0x10100000L
+    #if CRYPTOGRAPHY_OPENSSL_110_OR_GREATER
 
 Sometimes, the version of a library on a particular platform will have
 features that you thought it wouldn't, based on its version.