docs(all): mention DOTNET_TieredPGO in help text - #5139

Unknown scope "cli" found in pull request title "docs(cli): mention DOTNET_TieredPGO in help text". Scope must match one of: (?:all|(?:js|ts|dart|python|rust|beam|standalone|php)(?:/(?:js|ts|dart|python|rust|beam|standalone|php))*).