Show number of categories in setting summary

app/src/main/java/eu/kanade/tachiyomi/ui/setting/SettingsLibraryController.kt

@@ -171,6 +171,10 @@ class SettingsLibraryController : SettingsController() {
 
             preference {
                 titleRes = R.string.action_edit_categories
+
+                val catCount = db.getCategories().executeAsBlocking().size
+                summary = context.resources.getQuantityString(R.plurals.num_categories, catCount, catCount)
+
                 onClick {
                     router.pushController(CategoryController().withFadeTransaction())
                 }

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

@@ -186,6 +186,10 @@
     <string name="pref_category_library_categories">Categories</string>
     <string name="default_category">Default category</string>
     <string name="default_category_summary">Always ask</string>
+    <plurals name="num_categories">
+        <item quantity="one">%d category</item>
+        <item quantity="other">%d categories</item>
+    </plurals>
     <string name="pref_library_update_categories">Categories to include in global update</string>
     <string name="all">All</string>