html comment tag at the top of main documentation page may have one too many dashes at the beginning

https://github.com/apache/arrow-julia/blob/f8d2203b07380e1423723b5bfe32356aa1239284/docs/src/manual.md?plain=1#L1

The comment is visible on the [main documentation page](https://arrow.apache.org/julia/dev).

Start with docs/src/manual.md at line 1, linked in the issue, and inspect the HTML comment delimiter that appears on the main documentation page. Confirm the rendered result at the linked documentation page and ensure the comment is no longer visible.

Written by the indexing model from the issue text.