Convert docdock theme from submodule to native files and fix Hugo compatibility

themes/docdock/layouts/shortcodes/excerpt-include.html

@@ -0,0 +1,15 @@
+{{ $_hugo_config := `{ "version": 1 }` }}
+{{ $excerpt := findRE "(?ms){{%\\s*excerpt[^%]*%}}(.|\n)*?{{%\\s*/excerpt\\s*%}}" ( readFile (printf "./content/%s" (.Get "filename")) ) }}
+{{ range $excerpt }}
+	{{if ($.Get "panel")}}
+		<div class="panel panel-default">
+			<div class="panel-heading">{{$.Get "panel"}}</div>
+			<div class="panel-body">
+				{{ (replaceRE "(?ms){{%\\s*excerpt[^%]*%}}(.*){{%\\s*/excerpt\\s*%}}" "$1" .) | safeHTML | markdownify }}
+			</div>
+		</div>
+	{{else}}
+		{{ (replaceRE "(?ms){{%\\s*excerpt[^%]*%}}(.*){{%\\s*/excerpt\\s*%}}" "$1" .) | safeHTML | markdownify }}
+	{{ end }}
+{{ end }}
+{{.Inner}}