arptables: add page

[Umair-khurshid]

• The page(s) are in the correct platform directories: common, linux, osx, windows, sunos, android, etc.
• The page(s) have at most 8 examples.
• 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 title conforms to the recommended templates.
• Version of the command being documented (if known):

---

Adds a TLDR page for arptables, a tool for managing ARP filtering rules using the nftables backend.

This page includes examples for listing, adding, deleting, flushing rules, setting default policies, and saving configurations.

Based on: https://man7.org/linux/man-pages/man8/arptables-nft.8.html

[Managor]

Please create a fresh branch next time.

[Umair-khurshid]

Done!