feat: Show nested document count on document list items on collection home

app/components/DocumentListItem.js

@@ -23,6 +23,7 @@ type Props = {|
   document: Document,
   highlight?: ?string,
   context?: ?string,
+  showNestedDocuments?: boolean,
   showCollection?: boolean,
   showPublished?: boolean,
   showPin?: boolean,
@@ -44,6 +45,7 @@ function DocumentListItem(props: Props) {
   const [menuOpen, setMenuOpen] = React.useState(false);
   const {
     document,
+    showNestedDocuments,
     showCollection,
     showPublished,
     showPin,
@@ -104,6 +106,7 @@ function DocumentListItem(props: Props) {
           document={document}
           showCollection={showCollection}
           showPublished={showPublished}
+          showNestedDocuments={showNestedDocuments}
           showLastViewed
         />
       </Content>

app/components/DocumentMeta.js

@@ -27,6 +27,7 @@ type Props = {|
   showCollection?: boolean,
   showPublished?: boolean,
   showLastViewed?: boolean,
+  showNestedDocuments?: boolean,
   document: Document,
   children: React.Node,
   to?: string,
@@ -36,6 +37,7 @@ function DocumentMeta({
   showPublished,
   showCollection,
   showLastViewed,
+  showNestedDocuments,
   document,
   children,
   to,
@@ -123,6 +125,10 @@ function DocumentMeta({
     );
   };
 
+  const nestedDocumentsCount = collection
+    ? collection.getDocumentChildren(document.id).length
+    : 0;
+
   return (
     <Container align="center" {...rest}>
       {updatedByMe ? t("You") : updatedBy.name}&nbsp;
@@ -135,6 +141,12 @@ function DocumentMeta({
           </strong>
         </span>
       )}
+      {showNestedDocuments && nestedDocumentsCount > 0 && (
+        <span>
+          &nbsp;&middot; {nestedDocumentsCount}{" "}
+          {t("nested document", { count: nestedDocumentsCount })}
+        </span>
+      )}
       &nbsp;{timeSinceNow()}
       {children}
     </Container>

app/components/PaginatedDocumentList.js

@@ -11,6 +11,7 @@ type Props = {|
   options?: Object,
   heading?: React.Node,
   empty?: React.Node,
+  showNestedDocuments?: boolean,
   showCollection?: boolean,
   showPublished?: boolean,
   showPin?: boolean,