documentation for BigFloat

[alanedelman]

In looking at the doc for BigFloats etc
, couldn't find the default (256), and kind of a clue how to find it, but in a too vague way.
Suggest putting the default of 256 bits early in the doc, or at least, an example of what to type to find out.

[mgkuhn]

Adding a line-break in the 128-characters long function signature at the start of that docstring would make the precision::Integer=precision(BigFloat) keyword and its default value visible in HTML without horizontal scrolling.

More general issue: no pre-formatted line in a docstring should be longer than 80 characters.

[JeffreySarnoff]

We should avoid implying that BigFloats means 256 bits unless the user calls setprecision(BigFloat,n) . That is how Julia initializes BigFloat precision today. It may change tomorrow.