Change "API versioning" to "Versioning".

abernix · abernix · commit d921eef5d565 · 2018-05-31T14:24:45.000+03:00
The other titles in this section could mostly also have "API" in front of
them, so it seems better to leave this off (e.g. "API Security", "API
Monitoring", etc.).
diff --git a/docs/source/guides/versioning.md b/docs/source/guides/versioning.md
@@ -1,5 +1,5 @@
 ---
-title: API versioning
+title: Versioning
 description: Everything you need to know about evolving your GraphQL schema
 ---
 
