feat: rename custom icon pack from svg to custom

# To use custom SVG icons.
# Place custom SVG icon in `assets/images/icon-pack/`, creating folders if necessary.
[[feature]]
  icon = "beach-sunset"
  icon_pack = "custom"
  name = "Surfing"
  description = "90%"

See #1692

exampleSite/content/home/skills.md

@@ -43,7 +43,7 @@ subtitle = ""
 # Place custom SVG icon in `assets/images/icon-pack/`, creating folders if necessary.
 # [[feature]]
 #  icon = "beach-sunset"
-#  icon_pack = "svg"
+#  icon_pack = "custom"
 #  name = "Surfing"
 #  description = "90%"
 

layouts/partials/widgets/featurette.html

@@ -26,7 +26,7 @@
     <div class="featurette-icon">
       {{- if eq $pack "emoji" -}}
         {{- . | emojify -}}
-      {{- else if eq $pack "svg" -}}
+      {{- else if eq $pack "custom" -}}
         {{- $svg_icon := resources.Get (printf "images/icon-pack/%s.svg" .) -}}
         {{- if $svg_icon -}}<img src="{{ $svg_icon.RelPermalink }}" alt="{{.}}" class="svg-icon svg-baseline">{{- end -}}
       {{- else -}}