add some documentation structure

docs/index.md

@@ -1,5 +1,11 @@
 # CCCHH Infrastructure Documentation
 
-Home for CCCHH infrastructure documentation.
+Welcome, this is the home of the CCCHH infrastructure documentation.
+For an introduction, see the selection of important articles below:
+
+- [Who We Are and What We Do](./concepts-and-configurations/who-we-are.md)
+- [Onboarding](./guides/onboarding.md)
+- [Guides](./guides/index.md) for goal oriented step-by-step instructions.
+- [Concepts and Configurations](./concepts-and-configurations/index.md) for a explanations about how things work and why we things a certain way.
+- [Writing Documentation](./guides/writing-documentation.md)
 
-- **Guides**: Documentation on how to achieve various things.