Launch vscode, quick open(ctrl+p on windows, ⌘+p on mac), run "ext install markdown-authoring". Please note to enable it.
Features
Relative reference link validation
Auto-diagnostic when load extension and command(alt+l) support - show invalid relative reference links as severity warnings for all markdown files in workspace.
Auto-track when edit - also diagnostic for editing markdown files.
Intellegence - auto-detect and provide suggestions with valid relative reference link options when edit.