Certificate and Private Key Format: PKCS1 and PKSC8 certificate types need different private key header format

[jost0612]

Issue on page: https://github.com/opentelekomcloud-docs/elastic-load-balancing/blob/main/umn/source/certificate/certificate_and_private_key_format.rst

There are two versions of PKCS (Public-key Cryptography Standards): version 1 and version 8. For version #1 the keyword "RSA" is needed in the header and footer. For version #8 keyword "RSA" is not needed and upload fails if it is included.

The current help center document only refers to version 1, which is a pitfall if customers use version #8 and follow the documentation.

I suggest to modify the document to reflect how each version needs to be treated correctecly.

See also internal OTC internal incident ONS-12686 for reference.

Further reference: http://polarssl.org/kb/cryptography/asn1-key-structures-in-der-and-pem/