feat(whatis): recognize section suffix

[memchr]

Description

fast-syntax-highlighting now recognizes manual subsection suffixes such as open.2, ls.1p, printf.3 and highlight them correctly.

man-db is known to support subsection suffix. mandoc should not be affected by this commit.

Motivation and Context

manpage with subsection suffix is highlighted as error.

Related Issue(s)

Usage examples

How Has This Been Tested?

Tested with

• man-db 2.11.2
• mandoc 1.14.6

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• [ ] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.
• [ ] I have added tests to cover my changes.
• [x] All new and existing tests passed.