feat(11.1-04): add the Services section with a verified Queued jobs page

- docs/services/jobs.md: declaring, registering and dispatching jobs, the
  summer_jobs record, progress, cancellation and workers
- conga ExampleJob plus dispatch and status regions run by TestDocsDispatch
  on the package's Postgres harness (DocsApp in export_docs_test.go)
- concept map links the queued jobs row; services/jobs is a required page

modules/conga/export_docs_test.go

@@ -0,0 +1,18 @@
+package conga
+
+import (
+	"testing"
+
+	"git.golem15.com/golem15/summercms/modules/backpack"
+	"gorm.io/gorm"
+)
+
+// DocsApp returns an app and its GORM handle on a fresh migrated database
+// of this package's Postgres harness, for the database-backed docs examples
+// in example_test.go. It skips under -short and fails when the harness has
+// no database, like the package's other database tests.
+func DocsApp(t *testing.T) (*backpack.App, *gorm.DB) {
+	t.Helper()
+	db, dsn := migratedDB(t)
+	return testApp(t, db, dsn, nil)
+}