Add "Out of date" warnings to all Pipelines v1 docs

[hbelmiro]

{{% alert title="Old Version" color="warning" %}}
This page is about __Kubeflow Pipelines V1__, for information about __Kubeflow Pipelines V2__, please see the [new docs](__root_link_to_v2_docs__).

Please note that Kubeflow Pipelines V2 supports running V1 pipelines in a [backwards compatible mode](__page_which_explains_this__).
{{% /alert %}}

[thesuperzapper]

Cross-posting from #3737 (comment)

All of the pages under the pipeline's section which contain {{% alert title="Out of date" color="warning" %}} need to have it removed, there are currently 5 in master:

• Component Specification
  • You removed this one already.
• Best Practices for Designing Components
• DSL Recursion
• Using environment variables in pipelines
• Manipulate Kubernetes Resources as Part of a Pipeline
  • Looking at this one, we also need to create a V2 version of this, because its changed a lot.
  • See Move (and update) Pipelines pages from Legacy (v1) to Pipelines root #3750 (comment)

[hbelmiro]

/area pipelines

[hbelmiro]

/assign @hbelmiro