The doc comment for Keyvault certificate client model CertificateContentType could be improved

[ahsonkhan]

The use of getsecret doesn't seem appropriate in this doc. This applies to both C++ and even .NET.

One fix might be to just copy what's in the swagger, verbatim.
Or, maybe it is supposed to be GetCertificate since CertificateClient doesn't have a GetSecret anyway.

azure-sdk-for-cpp/sdk/keyvault/azure-security-keyvault-certificates/inc/azure/keyvault/certificates/certificate_client_models.hpp

Lines 396 to 400 in 4ab6a41

	/**
	* @brief Content type of the certificate when downloaded from getsecret.
	*
	*/
	class CertificateContentType final {

cc @heaths, @gearama

Looks like this doc comment was incorrectly copied from .NET:
https://github.com/Azure/azure-sdk-for-net/blob/cb3e8630ab0df6609b5ff6643e5ea0700e4a9816/sdk/keyvault/Azure.Security.KeyVault.Certificates/src/CertificateContentType.cs#L10

Azure/azure-sdk-for-net#7530

Here's the corresponding swagger:
https://github.com/Azure/azure-rest-api-specs/blob/3e27c70e7c02c07b458bc0e94716c3d82d3fdd19/specification/keyvault/data-plane/Microsoft.KeyVault/stable/7.3/certificates.json#L1387

      "description": "The content type of the secret. eg. 'application/x-pem-file' or 'application/x-pkcs12', "

@schaabs and @vhvb1989 what is the correct/intended documentation here?

Originally posted by @ahsonkhan in #4255 (comment)

[heaths]

The comment is technically correct. When you download the managed secret - the backing certificate, if you will - that content type does describe whether it's a base64-encoded PFX or ASCII PEM file. But, true, the docs could be reformatted to actually say something like "when the managed secret is downloaded using a SecretClient".