chore: drop the unused indexing_label string

app/src/main/res/values-ru/strings.xml

@@ -12,7 +12,6 @@
     <string name="language_english">Английский</string>
     <string name="language_russian">Русский</string>
     <string name="language_system">Системный</string>
-    <string name="indexing_label">Индексация словарей</string>
     <string name="clear_search">Очистить поиск</string>
     <string name="article_no_selected">Статья не выбрана</string>
     <string name="article_return_to_search">Вернуться к поиску</string>

app/src/main/res/values/strings.xml

@@ -12,7 +12,6 @@
     <string name="language_english">English</string>
     <string name="language_russian">Russian</string>
     <string name="language_system">System</string>
-    <string name="indexing_label">Indexing dictionaries</string>
     <string name="clear_search">Clear search</string>
     <string name="article_no_selected">No article selected</string>
     <string name="article_return_to_search">Return to search</string>