Import kubernetes/community docs (#6863)

* Import docs from other repos

* imported test docs

* fix README copy

* Add ToC YAML and index page for imported docs.

* modify update-imported-docs.sh

* Add `imported` to global ToCs

* Add nav to imported section

* remove unnecessary scope for docs/imported

* update script w/ comments and directory root fixes

* use genCmd variable

* display output of generation command

* Update instructions

* Add Community to /docs/imported/index.md

* fix travis errors

* update README.md and fix community docs issues

* simplify code, add comment

* make sure the binary is used instead of `go run`

* add automated handling for links from imported files

_data/globals.yml

@@ -8,3 +8,4 @@ tocs:
 - reference
 - samples
 - support
+- imported

_data/imported.yml

@@ -0,0 +1,11 @@
+bigheader: "Imported Docs"
+abstract: "Docs imported from other Kubernetes SIGs and repos."
+toc:
+- docs/imported/index.md
+
+- title: Community
+  section:
+  - docs/imported/community/guide.md
+  - docs/imported/community/devel.md
+  - docs/imported/community/mentoring.md
+  - docs/imported/community/keps.md