Add a 'name in series' helper to re-use logic

Signed-off-by: Danila Fedorin <danila.fedorin@gmail.com>

layouts/partials/nameinseries.html

@@ -0,0 +1,8 @@
+{{- $term := index (.page.GetTerms "series") 0 -}}
+{{- $divider := $term.Params.divider -}}
+{{- if (and $divider (strings.Contains .page.Title $divider)) -}}
+{{- $rest := after 1 (split .page.Title $divider) -}}
+{{- .scratch.Set "name" (delimit $rest $divider) -}}
+{{- else -}}
+{{- .scratch.Set "name" .page.Title -}}
+{{- end -}}