IO::Buffer improvements and documentation.

[ioquatix]

Tidy up the documentation of the C implementation.

[nobu]

Doesn't look documentation only?

[ioquatix]

You are correct, I reorganised and made some minor improvements of the code too.

[nobu]

We usually don’t end error messages with exclamation (or period).

[ioquatix]

Have we documented this anywhere? I suggest we add documentation around conventions that we expect to be followed in CRuby (e.g. naming conventions, exception messages, code organisation, etc). We can change these messages, however I prefer to have clear exclamations when reporting errors. Currently, there are a number of places in the code that follow this convention.

[ioquatix]

Maybe we can reference something like this: https://learn.microsoft.com/en-us/dotnet/standard/exceptions/best-practices-for-exceptions

Use grammatically correct error messages
Write clear sentences and include ending punctuation. Each sentence in the string assigned to the Exception.Message property should end in a period. For example, "The log table has overflowed." would be an appropriate message string.