Document macOS Web Cmdlet Limitations for 6.0.0

[markekraus]

• Need to document the use of brew installed libcurl+openssl+gssapi for Web Cmdlets -SslProtocol feature
• document limitation that multiple protocols cannot be supplied to -SslProtocol on macOS
• document that -Certificate is not supported on macOS

Issue Details

Version(s) of document impacted

• Impacts 6 document
• Impacts 5.1 document
• Impacts 5.0 document
• Impacts 4.0 document
• Impacts 3.0 document

Reason(s) for not selecting all version of documents

• The documented feature was introduced in selected version of PowerShell
• This issue only shows up in selected version of the document