docs(roadmap): use an image for now

there seem to be many interrelated issues with material mkdocs mermaid
support and the mermaid timeline diagram type which are preventing this
chart from rendering correctly in the deployed version of the docs site

docs/enrollment-pathways/README.md

@@ -16,45 +16,7 @@ See our [Milestones][milestones] for current work tracked against specific featu
 
 See our Product Roadmap for more information on planned feature development and prioritization.
 
-```mermaid
-timeline
----
-title: Cal-ITP Benefits Product Roadmap
-----
-%% Cal-ITP Benefits Epics (2024)
-          section 2024
-
-          Q1<br>Now
-          : Benefits admin tool (Foundation)
-        %%: SacRT - Launch Older Adults enrollment pathway
-          : SBMTD - Launch Mobility Pass enrollment pathway
-          : Release low-income riders enrollment pathway
-          : Migrate to Littlepay Backoffice API
-
-          Q2<br>Next
-          : Benefits admin tool (Agency configuration)
-          : Release enhancements to Veterans pathway
-          : Support for expiring benefits (low-income)
-
-          Q3<br>Planned
-          : Benefits admin tool (Agency users)
-          : Benefits admin tool (In-person eligibility verification)
-          : Release Medicare cardholder enrollment pathway
-
-          Q4<br>Planned
-          : Release riders with disabilities enrollment pathway
-
-%% Cal-ITP Benefits Epics (2025)
-          section 2025
-
-          Q1
-          : Support benefits reciprocity between CA transit agencies
-          : Implement evolved organizing principles for app UX
-
-          Q2
-          : Support for multiple payment processors
-          : Integration with all MSA payment processors
-```
+![Cal-ITP Benefits Product Roadmap](img/roadmap.png)
 
 [board]: https://github.com/orgs/cal-itp/projects/8/views/1
 [milestones]: https://github.com/cal-itp/benefits/milestones