There are relatively few truly open source ERP systems that are on the market. The 2-3 among them are OfBix (maintained by Apache Foundation), Adempiere derivatives (with no home) & ERPNext maintained by ERPNext foundation & Frappe.

ERPNext + Frappe Framework can do many things out of the box including act as a static site generator.  In fact the entire documentation is published using GitHub repository + Frappe Application generating the content. 

Is it a static site generator?

If you are asking whether it is a Static Site Generator (SSG), the simple answer is a pointer to their documentation website

A beautiful example of site created using ERPNext / Frappe Framework

The documentation of ERPNext has markdown files and images & is combined and generated by a FRAPPE application.

Find the source on Github 

The GitHub link to their website with the underlying site generator can be found here :