Documented Response of /wikis/home should be a wiki object and not an array

What does this MR do?

Response of getting a particular wiki page through the ce API is documented incorrectly as an array of wiki objects instead of a single wiki object. This MR makes the small change in the json response and updates the correct one.

What are the relevant issue numbers?

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• Tests added for this feature/bug
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the database guides
• Link to e2e tests MR added if this MR has Requires e2e tests label. See the Test Planning Process.