replace missing markdownify by RenderString

exampleSite/content/shortcodes/includes.md

@@ -32,7 +32,7 @@ Attributes:
 
 ### Include \*.md file
 
-Included markdown files will be rendered using the `markdownify` filter.
+Included markdown files will be rendered using the `RenderString` [function](https://gohugo.io/functions/renderstring/).
 
 {{< hint warning >}}
 **Location of markdown files**\

layouts/shortcodes/img.html

@@ -33,7 +33,7 @@
             {{ end }}/>
     </a>
     {{ with $caption }}
-    <figcaption>{{ . }}{{ with $source.Params.credits }} ({{ . | markdownify }}){{ end }}</figcaption>
+    <figcaption>{{ . }}{{ with $source.Params.credits }} ({{ . | $.Page.RenderString }}){{ end }}</figcaption>
     {{ end }}
 </figure>
 </div>

layouts/shortcodes/include.html

@@ -1,4 +1,4 @@
-{{$file := .Get "file"}}
+{{ $file := .Get "file" }}
 <div class="gdoc-include">
 {{- if eq (.Get "markdown") "true" -}}
 {{- $file | readFile | $.Page.RenderString -}}