Add two versioning shortcodes.

themes/psh-docs/layouts/shortcodes/version/only.html

@@ -0,0 +1,10 @@
+<!-- Markdown passed between shortcode `vendor/inner` will render only if the current version = first passed variable -->
+<!-- For example, -->
+<!-- {{< vendor/only "1" >}} -->
+<!-- platform variable:get  -->
+<!-- {{< /vendor/only >}} -->
+<!-- When the site is built, the `platform` command will appear iff vendor.config.version = 1 in params.yaml -->
+{{- $version := .Site.Params.vendor.config.version -}}
+{{- if eq $version ( int (.Get 0)) -}}
+    {{- .Inner | .Page.RenderString -}}
+{{- end -}}

themes/psh-docs/layouts/shortcodes/version/specific.html

@@ -0,0 +1,18 @@
+<!-- Markdown processes 2 versions, rendering only if key matches current version -->
+<!-- Key 1: Version 1; the first Inner prior to the dividing character -->
+<!-- Key 2: Version 2; the second Inner after the dividing character -->
+<!-- For example, -->
+<!-- {{< vendor/specific >}} -->
+<!-- platform variable:get  -->
+<!-- \<---\>  -->
+<!-- friday variable:get -->
+<!-- {{< /vendor/specific}} -->
+{{- $page := .Page -}}
+{{- $version := .Site.Params.vendor.config.version -}}
+{{- $splitVersionChar := "<--->" -}}
+{{- range $k, $v := split .Inner $splitVersionChar -}}
+    {{- $current := add $k 1 -}}
+    {{- if eq $current $version -}}
+{{- $v | $page.RenderString -}}
+    {{- end -}}
+{{- end -}}