mpt_holders documentation needs some cleanup

[mDuo13]

These issues with the mpt_holders reference page:

1. It should use {% tabs %} components to put the request/response format examples in tabs.
2. The page has some examples of tx and account_objects responses. I'm not sure why there are responses from other API methods in the reference page for this method. Maybe they're copy-paste errors or maybe there's some additional context missing.
3. The "Type" column for the fields doesn't use title case like our other reference pages do. It also doesn't link to common type definitions (e.g. markers and pagination, string number, ledger index, etc.)
4. Saying the mpt_amount is "base 10-encoded" is confusing. It's just a string number. (It's base-10 because that's, like, a normal number as opposed to hexadecimal or something. But making it sound like base58 decoding is probably going to more confusing than helpful.)
5. There is some inconsistent use of code font in instances of "MPToken object" or rippled.
6. The other Clio methods all have a badge that tells you what Clio version they were added in. This one is probably newer than many of those but it doesn't have a badge. This also makes it easier to miss that it's a Clio-specific method. (It is in the "Clio Methods" category, but I certainly missed that on first read. Maybe that's just because I was coming from [JA] MPToken #2925 instead of finding the page more organically.)
7. It would be great to add a "Try It" button and example on the WebSocket tool, and in the process double check the request and response formats, but that's not as easy as I would like at the moment since it's a Clio-only method for a feature that's only on Devnet right now. I think there are some Clio Devnet servers somewhere but I don't know the URL. Might be worth investigating.