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

OWNERS_ALIASES

@@ -48,6 +48,14 @@ aliases:
     - stewart-yu
     - xiangpengzhao
     - zhangxiaoyu-zidif
+  sig-docs-es-owners: # Admins for Spanish content
+    - raelga
+    - alexbrand
+  sig-docs-es-reviews: # PR reviews for Spanish content
+    - raelga
+    - alexbrand
+    - glo-pena
+    - electrocucaracha
   sig-docs-fr-owners: # Admins for French content
     - sieben
     - perriea
@@ -136,4 +144,3 @@ aliases:
     - xichengliudui
     - zhangxiaoyu-zidif
     - pigletfly
-