Rename mtt_update to mod_translation_updater (#13952)

Clarifies the purpose of the translation update script by giving it a more explanatory name.

doc/lua_api.md

@@ -4006,9 +4006,9 @@ Translations
 Texts can be translated client-side with the help of `minetest.translate` and
 translation files.
 
-Consider using the script `util/mtt_update.py` in the Minetest repository
-to generate and update translation files automatically from the Lua sources.
-See `util/README_mtt_update.md` for an explanation.
+Consider using the script `util/mod_translation_updater.py` in the Minetest
+repository to generate and update translation files automatically from the Lua
+sources. See `util/README_mod_translation_updater.md` for an explanation.
 
 Translating a string
 --------------------

util/README_mod_translation_updater.md

@@ -1,4 +1,4 @@
-# `mtt_update.py`—Minetest Translation Updater
+# `mod_translation_updater.py`—Minetest Mod Translation Updater
 
 This Python script is intended for use with localized Minetest mods, i.e., mods that use
 `*.tr` and contain translatable strings of the form `S("This string can be translated")`.
@@ -111,7 +111,7 @@ the locale files in an entire game.
 
 It has the following command line options:
 
-    mtt_update.py [OPTIONS] [PATHS...]
+    mod_translation_updater.py [OPTIONS] [PATHS...]
 
     --help, -h: prints this help message
     --recursive, -r: run on all subfolders of paths given