fix(121): fix typo (#379)

Author: toumorokoshi

aep/general/0121/aep.md.j2

@@ -100,8 +100,8 @@ request which mutates the resource is completed.
 
 Examples of strong consistency include:
 
-- Following a successful create that is is latest mutation on a resource, a get
-  request for a resource **must** return the resource.
+- Following a successful create that is the latest mutation on a resource, a
+  get request for a resource **must** return the resource.
 - Following a successful update that is the latest mutation on a resource, a
   get request for a resource **must** return the final values from the update
   request.