Add Japanese translation (ja) (#4019)

Author: skkzsh

changedetectionio/languages.py

@@ -37,6 +37,7 @@ def get_timeago_locale(flask_locale):
         'no': 'nb_NO',      # Norwegian Bokmål
         'hi': 'in_HI',      # Hindi
         'cs': 'en',         # Czech not supported by timeago, fallback to English
+        'ja': 'ja',         # Japanese
         'uk': 'uk',         # Ukrainian
         'en_GB': 'en',      # British English - timeago uses 'en'
         'en_US': 'en',      # American English - timeago uses 'en'

changedetectionio/translations/README.md

@@ -76,6 +76,7 @@ These commands read settings from `../../setup.cfg` automatically.
 - `en_US` - English (US)
 - `fr` - French (Français)
 - `it` - Italian (Italiano)
+- `ja` - Japanese (日本語)
 - `ko` - Korean (한국어)
 - `zh` - Chinese Simplified (中文简体)
 - `zh_Hant_TW` - Chinese Traditional (繁體中文)