Add insertpages shortcode

This is an improvement over the `readfiles` shortcode in that it allows to insert content files that contain shortcodes themselves.

This new shortcode is used to fix a regression introduced in https://github.com/gohugoio/hugoDocs/pull/1442 (`new-in` shortcode was not rendered as intended).

content/en/variables/page.md

@@ -204,7 +204,7 @@ aliased form `.Pages`.
 
 ### `.Pages` compared to `.Site.Pages`
 
-{{< readfile file="/content/en/readfiles/pages-vs-site-pages.md" markdown="true" >}}
+{{< insertpages path="readfiles/pages-vs-site-pages.md" >}}
 
 ## Page-level Params
 

content/en/variables/site.md

@@ -127,7 +127,7 @@ You can use `.Site.Params` in a [partial template](/templates/partials/) to call
 
 ### `.Site.Pages` compared to `.Pages`
 
-{{< readfile file="/content/en/readfiles/pages-vs-site-pages.md" markdown="true" >}}
+{{< insertpages path="readfiles/pages-vs-site-pages.md" >}}
 
 
 

layouts/shortcodes/insertpages.html

@@ -0,0 +1,21 @@
+<!-- {{/*
+Insert page `.Content` from a (headless) bundle; you can insert `.Content` from multiple page resources of the same bundle by specifying `glob`
+
+Usage: {{< insertpages path="PATH/TO/MD_FILE" >}}
+       {{< insertpages path="PATH/TO/BUNDLE" glob="*_PATTERN.md" >}}
+*/}} -->
+{{ $path := .Get "path" -}}
+{{ $glob := .Get "glob" -}}
+
+{{ $scratch := newScratch -}}
+{{ with $glob -}}
+  {{ $bundle := site.GetPage (path.Join $path "index.md") -}}
+  {{ $scratch.Set "pages" ($bundle.Resources.Match $glob) -}}
+{{ else -}}
+  {{ $bundle := site.GetPage (path.Join (path.Dir $path) "index.md") -}}
+  {{ $scratch.Set "pages" ($bundle.Resources.Match (path.Base $path)) -}}
+{{ end -}}
+
+{{ range ($scratch.Get "pages") -}}
+  {{ .Content }}
+{{ end -}}