Add README for VaGovBuildTrigger Module

docroot/modules/custom/va_gov_build_trigger/README.md

@@ -1,2 +1,37 @@
 # VaGovBuildTrigger
-VA.gov Build Trigger Module.
+
+The VaGovBuildTrigger module is a crucial component in the VA.gov content publishing workflow.
+
+## 1. Purpose
+
+- It's responsible for triggering the build process that publishes content from the Drupal CMS to the public-facing VA.gov website
+
+## 2. Architecture Context
+
+- VA.gov is a static site hosted on S3 with HTML, CSS, JavaScript and images
+- The CMS is built on Drupal 10 and acts as both a content management tool and an API server
+- Content builds are executed through the content-build project which pulls content via GraphQL and other APIs
+
+## 3. Importance
+
+- It's a key part of the decoupled architecture, bridging the gap between content creation in the CMS and publication to VA.gov
+- Enables the continuous integration process where content changes trigger new builds
+- Works with GitHub Actions to initiate builds that generate static assets which get deployed to S3
+
+## 4. Integration Points
+
+- Interfaces with the content-build repository
+- Works alongside other modules like va_gov_content_release to manage the content deployment pipeline
+- Coordinates with both development environments and production systems (prod.cms.va.gov)
+
+The module is essential for maintaining the automated, decoupled publishing workflow that powers VA.gov's content management system.
+
+```mermaid
+graph LR
+    CMS[VA.gov CMS<br/>Drupal 10] -->|GraphQL API| CB[content-build]
+    CMS -->|JSON API| CB
+    CB -->|Triggers| GHA[GitHub Actions]
+    GHA -->|Builds static files| Build[HTML/CSS/JS/images]
+    Build -->|Deploys to| S3[Amazon S3]
+    S3 -->|Serves| Web["<a href='https://www.va.gov'>www.va.gov</a>"]
+```