Addressed feedback PR

password is required
removed "successful" from login description in object
added optional true for username

Author: Josh Sager

docs/src/data/endpoints/managed.yaml

@@ -199,6 +199,7 @@ endpoints:
               A unique label describing the credential being added.
           username:
             type: String
+            optional: true
             description: >
               An optional login username.
           password:

docs/src/data/objects/managedcredential.yaml

@@ -22,7 +22,7 @@ schema:
   last_decryption:
     type: Object
     description: >
-      The username and datetime of the last successful login using this credential.
+      The username and datetime of the last login using this credential.
     who:
       type: String
       value: myusername