Improve table spec page's table formatting

need to properly render table cells on the same line, otherwise longer strings like "decimal(P,S)" might be split into multiple lines

_Originally posted by @kevinjqliu in https://github.com/apache/iceberg/pull/16798#discussion_r3408549397_

Start from the table spec page and review the formatting issue shown in the linked image and referenced pull-request discussion. Update the table rendering so each cell stays on one line, including longer strings such as "decimal(P,S)", and verify the page visually.

Written by the indexing model from the issue text.