DOC: ssl: Use consistent naming for TLS protocols

In most cases, "TLSv1.x" naming is used across and documentation, lazy
people tend to grep too much and may not find what they are looking for.

Fixing people is hard.
diff --git a/doc/configuration.txt b/doc/configuration.txt
index d11b631..4e66aad 100644
--- a/doc/configuration.txt
+++ b/doc/configuration.txt
@@ -10541,7 +10541,7 @@
   setting of which client is allowed to use the protocol.
 
 allow-0rtt
-  Allow receiving early data when using TLS 1.3. This is disabled by default,
+  Allow receiving early data when using TLSv1.3. This is disabled by default,
   due to security considerations.
 
 alpn <protocols>