Remove example about default credentials from A05 2021

[drhankey]

As example for security misconfiguration is listed "Default accounts and their passwords are still enabled and unchanged". However, this is part of A07, specifically CWE-1392 Use of Default Credentials.

I suggest to remove this line:

Top10/2021/docs/A05_2021-Security_Misconfiguration.md

Line 27 in 7c7288f

- Default accounts and their passwords are still enabled and