Update-MarkdownCommandHelp duplicates Parameter content if HelpMessage is specified

Prerequisites

• Write a descriptive title.
• Make sure you are able to repro it on the latest version
• Search the existing issues.

Steps to reproduce

Expected behavior

If the first line exactly matches the HelpMessage, preserve everything below (to enable the addition of additional context to the MD file)

If the first line does not match the helpmessage, only update the first line. Maybe have a `-ReplaceParameterHelp` option to force a direct replacement if the helpmessage is updated.

Also the helpmessage part of the YAML isn't populated correctly

Actual behavior

See Above

Error details

N/A

Environment data

Name                           Value
----                           -----
PSVersion                      7.6.1
PSEdition                      Core
GitCommitId                    7.6.1
OS                             Microsoft Windows 10.0.26200
Platform                       Win32NT
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0…}
PSRemotingProtocolVersion      2.4
SerializationVersion           1.1.0.1
WSManStackVersion              3.0

Version

1.01

Visuals

No response

Start by reproducing the duplication with Update-MarkdownCommandHelp using a command whose HelpMessage is specified, then inspect the generated Markdown and YAML. Compare cases where the first line matches or differs from HelpMessage; done means additional Markdown context is preserved correctly, replacement is consistent with the requested behavior, and the YAML HelpMessage is populated correctly.