API reference improvements

[vilanz]

While the API reference right now works well, I think it could be more concise, especially when it comes to method typing and some inconsistent grammar/formatting.

I can't set up a pull request right now, but these are some sketches of what I came up with (still need to find a better way to include parameter types):

Parsing

Now Dayjs

Set to the current date and time by default.

dayjs();

Dayjs parsed from other date formats Dayjs

• ISO 8601 string

dayjs(String);
dayjs('1995-12-25');

• Unix Timestamp (milliseconds since the Unix Epoch - Jan 1 1970 12AM UTC)

dayjs(Number);
dayjs(1318781876406);

• native Javascript Date object

dayjs(Date);
dayjs(new Date(2018, 8, 18));

[ ... stuff ... ]

Get + Set

Get and set date.

Year number

dayjs().year();

Month number

dayjs().month();

[iamkun]

Thanks. Looks good to me.

I am keep looking a good way to make our docs better and simpler.

Actually, we had a discussion before, you could check it in #75.

Still, discussions welcome.