Document dependency path for Yarn 1.x

Update the Dependency List documentation
and add Yarn 1.x to the package managers
for which the dependency paths to vulnerable dependencies
are available.

See https://gitlab.com/gitlab-org/gitlab/-/issues/229473

doc/user/application_security/dependency_list/index.md

@@ -55,6 +55,7 @@ dependencies, but the UI only shows one of the shortest paths.
 Dependency Paths are supported for the following package managers:
 
 - [NuGet](https://www.nuget.org/)
+- [Yarn 1.x](https://classic.yarnpkg.com/lang/en/)
 
 ## Licenses