Update "debug" rpc help text

[UdjinM6]

Format help text to match current "template" a bit better:

• add Arguments and Result sections;
• category is not optional, should not be surrounded by ().

Also update debug categories list here to match the one in init.cpp while at it.

Thanks @thephez for pointing out.

[thephez]

A couple thoughts that may or may not be helpful 🙂

1. It might be nice to return the full list of debug categories enabled instead of the one just added? Not sure if that would be helpful or not.
2. It doesn't validate the category so you can enter anything and will never get an error. Could cause confusion for typos if the category is invalid.

[thephez]

Oh, also tACK 👍

[UdjinM6]

@thephez

1. Categories aren't added, they are replaced. If you need many categories you have to specify them all at once.
2. True but debug a (or some another non-existing category) is also helpful if you want to enable branches with if (fDebug) but don't want the spam from anything else for example ;) Maybe result could be a bit more explicit about this specific case though, I added a note. We could probably add some verification logic here later when debug categories will become enum.

[thephez]

re-ACK

[codablock]

utACK