bun-pm-cache: add page

[Ahamed1846]

• 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 title conforms to the recommended templates.
• Version of the command being documented (if known): latest

Reference: #19127

[msaf9]

@Managor, I believe that we can merge PRs #19580 and #19581 into one page, as they both relate to the cache aspect. Could you please confirm this?

[Managor]

Yes. The pages should be built from the bottom-up and subcommand pages should only be created when the root page overflows.