Put ledger objects into alphabetical order and minor improvements

[LimpidCrypto]

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Summary

This PR just adds some minor improvements such as fix a misspelling, fixes some nits and a false typing. It also addresses the issue #1183 and puts the ledger object fields in alphabetical order, regardless of wether they are optional or not.

Tasks

• [ ] I also like that the NFToken... objects have extra columns to tell if a field is optional. I find it way clearer than defining it in the fields description. Should I add an extra column to all ledger objects?
• [ ] If an object has the field Flags it is still possible the object has no flags. We should have a consistent description for these cases, including an explanation that the value is always 0.

[mDuo13]

I like what you've done here so far. I agree it would be good to have a consistent description for the case where no flags are defined, and I'm on board with adding a column to all object types to indicate whether a field is required or "optional". (I find the term "optional" to be a bit weird in some of these cases, because it implies that the user can omit it, but the actual meaning is that the object may or may not have it.) I guess it's fine if the column title is "Required" and the column contents are "Yes" or "No"

[LimpidCrypto]

I like it this way @mDuo13

I personally think the '(Option)' text sometimes gets lost between all the field descriptions. I would find a column 'Required', as @mDuo13 suggested, between types and description way clearer. But maybe that's just me.

[LimpidCrypto]

Since this is my first PR I could use some context why the Link Checker failed. A broken link in public API method account_nfts, but I didn't changed anything there. Thank you :)