message: docs(theme): update migration guide
diff: @@ -127,14 +127,18 @@ Since the theme no longer has a built-in search:
  ### Outlook
  -- clear `iconPrefix` default value from `icon-`.
  +- clear `iconPrefix` default value from `icon-`
  You now need to set this option according to icons you are using
  - If you use IconFont, you may need to set it to `iconfont icon-`
  - If you use FontAwesome, you may need to set it to `fa fa-`
  -- add `"enable"` in `darkmode` option
  +- update values of `darkmode` option
  +
  + - add `"enable"`
  + - rename `"switch"` to `"toggle"`
  + - rename `"auto-switch"` to `"switch"`
  ### Blog Config
  