Feature/markdown render

[MaxenceG2M]

A Markdown Render for issues.

Need PR #46

PR contains:

• A renaming of some contributions ID
• A Welcome View to explain that a refresh is needed
  • I hesitated to propose an automatic refresh when opening the Gitea view
  • Not really needed for this feature
• Markdown render
  • Use external markdown-it package
• Configuration to choose HTML or Markdown
• Markdown render show labels with color, and all assignees of a issue (if more than one)