[DDC-3073] Add documentation about how to map column options

Adding documentation about currently accepted column options in mappings. Also providing some more examples how to map column options for each driver.
Hmmm is that really so? AFAIK a custom D2 type that requires a comment will just extract the D2 information part from the comment and leave the original comment as is for the comparator, no? And AFAIK other options are also explicitly compared by the comparator so I don't see why the schema tool should have any problems with them. The only attribute I know that doesn't work with the schema tool is `columnDefinition` but that's not part of the options here.