fix(search): add index page of docs to search index

Allows to search content on the main page of docs/tutorials/courses.

Previously, all docs pages except the main page were indexed.

layouts/index.json

@@ -1,16 +1,28 @@
-{{/* Generate the search index. */}}
-{{- $scr := $.Scratch -}}
-{{- $scr.Add "index" slice -}}
-{{- range (where .Site.RegularPages "Section" "!=" "home") -}}
+{{- /* Generate the search index. */ -}}
+{{- $index := slice -}}
+{{- $pages := where .Site.RegularPages "Section" "!=" "home" -}}
+{{- $pages := $pages | union (where (where .Site.Pages "Kind" "section") "Type" "docs") -}}
+{{- /* TODO: Add author pages to index so their bios can be searched. */ -}}
+{{- /* $pages := $pages | union (where (where .Site.Pages "Kind" "taxonomy") "taxonomyTerm" "author") */ -}}
+
+{{- range $pages -}}
+  {{- /* Do not index drafts or private pages. */ -}}
   {{- if and (not .Draft) (not .Params.private) -}}
-    {{- if .Params.abstract -}}
-      {{- $scr.Set "summary" .Params.abstract -}}
-    {{- else if .Params.summary -}}
-      {{- $scr.Set "summary" .Params.summary -}}
+
+    {{- /* Generate page description. */ -}}
+    {{- $desc := "" -}}
+    {{- if .Params.summary -}}
+      {{- $desc = .Params.summary -}}
+    {{- else if .Params.abstract -}}
+      {{- $desc = .Params.abstract -}}
     {{- else -}}
-      {{- $scr.Set "summary" .Summary -}}
+      {{- $desc = .Summary -}}
     {{- end -}}
-    {{- $scr.Add "index" (dict "objectID" .UniqueID "date" .Date.UTC.Unix "publishdate" .PublishDate "lastmod" .Lastmod.UTC.Unix "expirydate" .ExpiryDate.UTC.Unix "lang" .Lang "permalink" .Permalink "relpermalink" .RelPermalink "title" .Title "summary" (plainify ($scr.Get "summary")) "content" .Plain "authors" .Params.Authors "kind" .Kind "type" .Type "section" .Section "tags" .Params.Tags "categories" .Params.Categories)}}
+
+    {{- /* Add page to index. */ -}}
+    {{- $index = $index | append (dict "objectID" .UniqueID "date" .Date.UTC.Unix "publishdate" .PublishDate "lastmod" .Lastmod.UTC.Unix "expirydate" .ExpiryDate.UTC.Unix "lang" .Lang "permalink" .Permalink "relpermalink" .RelPermalink "title" .Title "summary" (plainify $desc) "content" .Plain "authors" .Params.Authors "kind" .Kind "type" .Type "section" .Section "tags" .Params.Tags "categories" .Params.Categories) -}}
+
   {{- end -}}
 {{- end -}}
-{{- $scr.Get "index" | jsonify -}}
+
+{{- $index | jsonify -}}