feat: add help message for removing shortcuts in keymap settings

src/main/resources/i18n/messages.properties

@@ -114,7 +114,7 @@ termora.settings.keymap=Keymap
 termora.settings.keymap.shortcut=Shortcut
 termora.settings.keymap.action=Action
 termora.settings.keymap.already-exists=The shortcut [{0}] is already in use by [{1}]
-
+termora.settings.keymap.question=Select a line, press the <font color=rgb({0},{1},{2})> ⌫ (Backspace)</font> key to remove the shortcut
 
 termora.settings.sftp.edit-command=Edit Command
 termora.settings.sftp.db-click-behavior=Double-click

src/main/resources/i18n/messages_ru_RU.properties

@@ -99,7 +99,7 @@ termora.settings.keymap=Горяиче клавиши
 termora.settings.keymap.shortcut=Комбинация
 termora.settings.keymap.action=Команда
 termora.settings.keymap.already-exists=Комбинация [{0}] уже используется [{1}]
-
+termora.settings.keymap.question=Выберите строку и нажмите <font color=rgb({0},{1},{2})> ⌫ (клавишу Backspace)</font>, чтобы удалить сочетание клавиш
 
 termora.settings.sftp.edit-command=Редактировать команду
 termora.settings.sftp.db-click-behavior=двойной щелчок

src/main/resources/i18n/messages_zh_CN.properties

@@ -125,7 +125,7 @@ termora.settings.keymap=键盘
 termora.settings.keymap.shortcut=快捷键
 termora.settings.keymap.action=操作
 termora.settings.keymap.already-exists=快捷键 [{0}] 已经被 [{1}] 占用
-
+termora.settings.keymap.question=选中一行，按下 <font color=rgb({0},{1},{2})> ⌫ (退格键)</font> 移除快捷键
 
 termora.settings.sftp.edit-command=编辑命令
 termora.settings.sftp.db-click-behavior=双击行为

src/main/resources/i18n/messages_zh_TW.properties

@@ -55,6 +55,7 @@ termora.settings.keymap=鍵盤
 termora.settings.keymap.shortcut=快捷鍵
 termora.settings.keymap.action=操作
 termora.settings.keymap.already-exists=快捷鍵 [{0}] 已經被 [{1}] 占用
+termora.settings.keymap.question=選取一行，按下 <font color=rgb({0},{1},{2})> ⌫ (退格鍵)</font> 移除快速鍵
 
 termora.settings.sftp.edit-command=編輯命令
 termora.settings.sftp.db-click-behavior=按兩下行為