fixed a problem of 'reward and wechat-subscriber'

[kuleyu]

fixed the problem that the images of 'reward and wechat-subscriber area' can't display when the main '_config.yml' set 'root: /xxxxxx/'

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines.
• Tests for the changes have been added (for bug fixes / features).
  • Muse | Mist have been tested.
  • Pisces | Gemini have been tested.
• Docs have been added / updated (for bug fixes / features).

PR Type

What kind of change does this PR introduce?

• Bugfix.
• Feature.
• Code style update (formatting, local variables).
• Refactoring (no functional changes, no api changes).
• Build related changes.
• CI related changes.
• Documentation content changes.
• Other... Please describe:

What is the current behavior?

the images of 'reward and wechat-subscriber area' can't display when the main '_config.yml' set 'root: /xxxxxx/'
Issue Number(s): N/A

What is the new behavior?

Now if you set the main '_config.yml' as 'root: /xxxxxx/', the images of 'reward and wechat-subscriber area' can display correctly.

• Screens with this changes: N/A
• Link to demo site with this changes: https://kuleyu.github.io/hexolog/post/20990.html

How to use?

In NexT _config.yml:

...

Does this PR introduce a breaking change?

• Yes.
• No.

[ivan-nginx]

This NexT version not supported anymore (at least by me). For now it rebased under theme-next organization and have this path. So, u can do pull there.

More information in #2061 issue.