Reduce width of table in issue template

[fredden]

Description

This is a follow-up to https://github.com/squizlabs/PHP_CodeSniffer/pull/3829 based on the conversation therein following that being merged.

While the table looks good in a mono-spaced font, the input field on the new issue form in GitHub uses a variable width font, so the table doesn't line up nicely there. Having less white-space (and the lack of trailing pipe) should mean the information is easier to supply, and still displays nicely when rendered as Markdown.

Suggested changelog entry

None required

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)
  • [ ] This change is only breaking for integrators, not for external standards or end-users.
• [x] Documentation improvement

PR checklist

• [ ] I have checked there is no other PR open for the same change.
• [x] I have read the Contribution Guidelines.
• [x] I grant the project the right to include and distribute the code under the BSD-3-Clause license (and I have the right to grant these rights).
• [ ] I have added tests to cover my changes.
• [ ] I have verified that the code complies with the projects coding standards.
• [ ] [Required for new sniffs] I have added XML documentation for the sniff.
• [ ] [Required for new files] I have added any new files to the package.xml file.

[gsherwood]

Thanks @fredden - I agree that it's easier to complete the report now. Appreciate the PR.