Move to custom SSG instead of eleventy.

docs/read-page/helpers.js

@@ -0,0 +1,16 @@
+
+export async function contentAsText (doc, rootLevel, includeCurrent = false) {
+  const { level, next, line, head } = doc
+  const linesAsArray = []
+  if (includeCurrent) linesAsArray.push(line())
+  let contentDepth = includeCurrent ? level() : -1
+
+  while(await next(rootLevel)) {
+    if (contentDepth === -1 && !!line()) contentDepth = level()
+
+    const indent = ''.padStart(level() - contentDepth, ' ')
+    linesAsArray.push(indent + line())
+  }
+
+  return linesAsArray.join('\n')
+}