Update README.md

Author: mitzimorris

README.md

@@ -1,2 +1,8 @@
 # stan-website
-Do-over of mc-stan.org using quarto and mc-stan.org/docs theming
+The Stan project's web pages:  [mc-stan.org](https:/mc-stan.org)
+  + How to install Stan
+  + The Stan ecosystem of tools
+  + Learning Stan: tutorials, case-studies, and field guides
+  + Contributing to Stan
+
+The Stan documentation suite has its own repo:  [stan-dev/docs](https://github.com/stan-dev/docs)