migrate site content: contributing docs (#4709)

* migrate contributing docs

* modifies weight for ordering

* updates links and info based on feedback

* removes broken powershell link

* Update site/content/en/contribute/windows/_index.md

Co-authored-by: Katrina Verey <kn.verey@gmail.com>

* Update site/content/en/contribute/windows/_index.md

Co-authored-by: Katrina Verey <kn.verey@gmail.com>

* Update site/content/en/contribute/mac/_index.md

Co-authored-by: Katrina Verey <kn.verey@gmail.com>

* Update site/content/en/contribute/howitworks/_index.md

Co-authored-by: Katrina Verey <kn.verey@gmail.com>

* Update site/content/en/contribute/howitworks/_index.md

Co-authored-by: Katrina Verey <kn.verey@gmail.com>

* simplify build explanation

* removes windows docs

* removes community - duplicate

* update the tooling instructions

* point to proposal docs

* Update site/content/en/contribute/howitworks/_index.md

Co-authored-by: Katrina Verey <kn.verey@gmail.com>

site/content/en/contribute/community/_index.md

@@ -0,0 +1,23 @@
+---
+title: "Community Engagment"
+linkTitle: "Community"
+type: docs
+weight: 20
+description: >
+    Joining SIG-CLI and the Kubernetes community
+---
+
+[CLI special interest group]: https://github.com/kubernetes/community/tree/master/sig-cli#cli-special-interest-group
+[contributor roles]: https://github.com/kubernetes/community/blob/master/community-membership.md#community-membership
+[mailing list]: https://groups.google.com/forum/#!forum/kubernetes-sig-cli
+[bi-weekly meetings]: https://github.com/kubernetes/community/tree/master/sig-cli#meetings
+[slack channel]: https://kubernetes.slack.com/messages/sig-cli
+
+Kustomize is a sub project of the Kubernetes [CLI special interest group] and follows the Kubernetes
+project [contributor roles].
+
+If you are interested in contributing towards Kustomize or getting more involved with the community:
+
+- join the [mailing list] and reach out
+- join the [slack channel] and reach out
+- attend one of the [bi-weekly meetings] (alternating Wednesdays)