Init Spanish translation (#13543)

* Add OWNERS information for sig-docs-es

* Add spanish README file

* Add Spanish language section

* Add headless _common-resources section

* Add case-studies section

* Add docs section

* Add search page

* Add overview section

* Add main content page

* Add i18n strings for Spanish language

* Add alexbrand as OWNER and REVIEWER

* Add glo-pena as REVIEWER

* Add headless include section

* Add partners section

* Add blog section

* Add Code of Conduct manifests

* Add supported-doc-versions page

* Add community site

* Add sitemap

* Remove overview section

* Add initial home version

* Rework phrase

* Fix typo

* Add update-user-guid-links script

* Upload Spanish CoC updated version

https://github.com/cncf/foundation/commit/e2a956

* Rework phrase

* Fix typo in community index

* Fix informal person usage

* Translate sitemap page

* Add electrocucaracha as REVIEWER

* Add landing page for /es/docs

* Remove home pages from initial translation

* Upload Spanish CoC updated version

https://github.com/cncf/foundation/commit/6474dfd

* Add more information to the docs landing

content/es/includes/index.md

@@ -0,0 +1,3 @@
+---
+headless: true
+---