feat: support Hugo's change in behaviour of relURL/relLangURL

Hugo team changed behaviour of relURL/relLangURL, requiring removal of slash prefix to path

Fix built-in search results are empty when deploying site to domain's sub-folder

Fix #2985

modules/wowchemy/layouts/partials/site_js.html

@@ -112,7 +112,7 @@
   {{/* Configure search engine. */}}
   {{ $min_length := site.Params.features.search.wowchemy.min_length | default 1 }}
   {{ $threshold := site.Params.features.search.wowchemy.threshold | default 0.3 }}
-  {{ $search_config := dict "indexURI" ("/index.json" | relLangURL) "threshold" $threshold "minLength" $min_length }}
+  {{ $search_config := dict "indexURI" ("index.json" | relLangURL) "threshold" $threshold "minLength" $min_length }}
   {{ $search_i18n := dict "placeholder" (i18n "search_placeholder") "results" (i18n "search_results") "no_results" (i18n "search_no_results") }}
   {{ $content_types := dict "post" (i18n "posts") "project" (i18n "projects") "publication" (i18n "publications") "event" (i18n "talks") "slides" (i18n "slides") "authors" (i18n "authors") }}
   {{ $js_search_params = dict "search_config" $search_config "algoliaConfig" $algoliaConfig "i18n" $search_i18n "content_type" $content_types }}