Defaults: Deprecate DKOPTREADER_CONFIG_DOC_LANGS_TEXT

It's unused since #11977, dropping it ensures we no longer show it in
the advanced settings UI.

defaults.lua

@@ -88,7 +88,6 @@ DKOPTREADER_CONFIG_CONTRAST = 1.0,        -- range from 0.2 to 2.0
 DKOPTREADER_CONFIG_WORD_SPACINGS = {0.05, -0.2, 0.375},    -- range from (+/-)0.05 to (+/-)0.5
 DKOPTREADER_CONFIG_DEFAULT_WORD_SPACING = -0.2,            -- range from (+/-)0.05 to (+/-)0.5
 -- document languages for OCR
-DKOPTREADER_CONFIG_DOC_LANGS_TEXT = {"English", "Chinese"},
 DKOPTREADER_CONFIG_DOC_LANGS_CODE = {"eng", "chi_sim"},    -- language code, make sure you have corresponding training data
 DKOPTREADER_CONFIG_DOC_DEFAULT_LANG_CODE = "eng",          -- that have filenames starting with the language codes
 

frontend/ui/data/onetime_migration.lua

@@ -10,7 +10,7 @@ local util = require("util")
 local _ = require("gettext")
 
 -- Date at which the last migration snippet was added
-local CURRENT_MIGRATION_DATE = 20240731
+local CURRENT_MIGRATION_DATE = 20240911
 
 -- Retrieve the date of the previous migration, if any
 local last_migration_date = G_reader_settings:readSetting("last_migration_date", 0)
@@ -697,5 +697,16 @@ if last_migration_date < 20240731 then
     end
 end
 
+-- 20240911, Defaults: Deprecate DKOPTREADER_CONFIG_DOC_LANGS_TEXT after #11977, https://github.com/koreader/koreader/pull/12504
+if last_migration_date < 20240911 then
+    logger.info("Performing one-time migration for 20240911")
+
+    if G_defaults:hasBeenCustomized("DKOPTREADER_CONFIG_DOC_LANGS_TEXT") then
+        G_defaults:delSetting("DKOPTREADER_CONFIG_DOC_LANGS_TEXT")
+    end
+
+    G_defaults:flush()
+end
+
 -- We're done, store the current migration date
 G_reader_settings:saveSetting("last_migration_date", CURRENT_MIGRATION_DATE)