Hidden field documentation bug

[snidelytoo]

On Monday, May 8, 2017 at 2:07:01 PM UTC-7, Joe Barnhart wrote:
In the section about SQLFORM, the description of hidden fields is demonstrably wrong. The code example is:

form.vars.a = request.vars.a
form = SQLFORM(..., hidden=dict(a='b'))

Since the variable "form" is created on the second line, it is not available on the first as the target of an assignment.

[snidelytoo]

See pull request #357