support image caption switch

[zizdlp]

• add image caption
  • default not show the caption
  • set SHOW_CAPTION=true to show the caption
• remove linchat link

Checklist

• [x] Ensure that the code has passed all tests.
• [x] The PR description is clear and complete.
• [x] All relevant documentation has been updated.

Submission Type

• [ ] New language support
• [ ] Bug fix
• [x] Other