Fix truncated mermaid diagram text

Changed 'SSL Monitor Operation API' to 'SSL Monitor Operation' in the
mermaid diagram to prevent text truncation that was showing as
'SSL Monitor Operation AP' in the rendered output.

Signed-off-by: Nic Cope <[email protected]>

Author: negz

content/master/whats-crossplane/_index.md

@@ -242,7 +242,7 @@ flowchart TD
 user(User)
 
 subgraph control [Control Plane]
-  operation(SSL Monitor Operation API)
+  operation(SSL Monitor Operation)
   
   subgraph crossplane [Operation Engine]
     fn(Python Function)