fix blocks contained in the implicit root section not being added to index (#114)

Author: GamerGirlandCo

src/index/import/markdown.ts

@@ -184,7 +184,7 @@ export function markdownSourceImport(
     // In the second list pass, actually construct the list heirarchy.
     for (const item of listItems.values()) {
         if (item.parentLine < 0) {
-            const listBlock = blocks.get(-item.parentLine);
+            const listBlock = blocks.getPairOrNextHigher(-item.parentLine)![1];
             if (!listBlock || !(listBlock.type === "list")) continue;
 
             (listBlock as ListBlockData).items.push(item);