docs: additional shortcodes (#441)

* Create pdf.md

* Update pdf.md

* Escape PDF shortcode examples

* Remove markdown syntax highlight

* chore: update Hugo and Go versions for deployment

* docs: add additional shortcodes

* chore: re-compile

---------

Co-authored-by: Shahar Naveh <50263213+ShaharNaveh@users.noreply.github.com>

exampleSite/hugo_stats.json

@@ -27,6 +27,7 @@
       "head",
       "hr",
       "html",
+      "iframe",
       "img",
       "input",
       "kbd",
@@ -221,6 +222,7 @@
       "hextra-filetree",
       "hextra-filetree-folder",
       "hextra-footer",
+      "hextra-pdf",
       "hextra-scrollbar",
       "hextra-sidebar-collapsible-button",
       "hextra-tabs-panel",