[Typo] Fix typo in DOC (#545)

Author: ajanikow

docs/design/rotating.md

@@ -6,8 +6,8 @@ Rotation of ArangoDeployment Pods can be triggered by Pod deletion or by annotat
 
 Using annotation Pods gonna be rotated one-by-one which will keep cluster alive.
 
-Key: `deployment.arangodb.com/rotation`
+Key: `deployment.arangodb.com/rotate`
 Value: `true`
 
 To rotate ArangoDeployment Pod kubectl command can be used:
-`kubectl annotate pod arango-pod deployment.arangodb.com/rotation=true`
+`kubectl annotate pod arango-pod deployment.arangodb.com/rotate=true`