slabtop: add page

[zhb4]

Checklist

• The page(s) are in the correct platform directories: common, linux, osx, windows, sunos, android, etc.
• The page description(s) have links to documentation or a homepage.
• The page(s) follow the content guidelines.
• The page(s) follow the style guide.
• The PR contains at most 5 new pages.
• The PR is authored by me, or has been human-reviewed if it was created with AI or machine translation software.
• The PR title conforms to the recommended templates.
• Version of the command being documented (if known):

Reference issue: #

[tldr-bot]

The build for this PR failed with the following error(s) at commit
589c4e87eca95e3493c0899084e402a5c05015cd:

pages/linux/slabtop.md:4: TLDR003 Descriptions should start with a capital letter

Please fix the error(s) and push again.

[ivanbaluta]

Hi zhb4!
I've noticed one important issue that needs to be addressed. The slabtop command requires root privileges to read kernel slab information from /proc/slabinfo.
Please add sudo to the beginning of all the examples (except for the --help one). Without it, the commands will fail with a "Permission denied" error.

[ivanbaluta]

the --sort option expects a single character (e.g., c for cache size, o for number of objects), not a full word.

[ivanbaluta]

We could also add mnemonics to the sort descriptions