Docs: add product roadmap (#53)

My first PR! Woo! Adding product roadmap and basic info about our sprint/project space to the doc site.

Author: leelas-pm

Diff for: docs/README.md

@@ -3,3 +3,63 @@
 Caltrans Performance Measurement System
 
 PeMS is open-source software that is designed, developed, and maintained by [Compiler LLC](https://compiler.la) on behalf of Caltrans Traffic Operations.
+
+## Current Work
+
+We do sprint planning and track day-to-day work in our [Project Board](https://github.com/orgs/compilerla/projects/3/views/1).
+
+See our current [Milestones](https://github.com/compilerla/pems/milestones) for a higher level view of project progress.
+
+## Product Roadmap
+
+Our product roadmap captures what we're currently building, what we've built, and what we plan to build in future quarters. It is updated on a regular basis, aligned with project progress.
+
+```mermaid
+timeline
+    title PeMS Product Roadmap
+%% PeMS Epics (2024)
+          section 2024
+
+          Q3<br>Complete
+          : Project launch
+          : Established resources and overall scope
+          : Began discovery work
+
+          Q4<br>Now
+          : Confirm site architecture
+          : Create local environment
+          : Set up GitHub repository
+          : Scaffold app structure
+          : Create a prioritized backlog of features
+
+%% PeMS Epics (2025)
+          section 2025
+
+          Q1<br>Planned
+          : Create dev environment
+          : Create test environment
+          : Set up a working CI/CD pipeline
+          : Launch test version of site for Caltrans users
+
+          Q2<br>Planned
+          : Create production environment
+
+          Q3<br>Future
+          : Compiler contract ends July 2025
+
+%%{
+    init: {
+        'logLevel': 'debug',
+        'theme': 'default' ,
+        'themeVariables': {
+            'cScale0': '#ffa500', 'cScaleLabel0': '#000000',
+            'cScale1': '#ffff00', 'cScaleLabel1': '#000000',
+            'cScale2': '#ffff00', 'cScaleLabel2': '#000000',
+            'cScale3': '#008000', 'cScaleLabel3': '#ffffff',
+            'cScale4': '#0000ff', 'cScaleLabel4': '#ffffff',
+            'cScale5': '#4b0082', 'cScaleLabel5': '#ffffff',
+            'cScale6': '#000000', 'cScaleLabel6': '#ffffff'
+        }
+    }
+}%%
+```