Update IgnoreChangeTest documentation

[xqwzts]

My understanding of the ignoreChange code contradicts the provided dartdoc:

The doc states:

/// To ignore a change, provide a function that returns true or false. If the
/// returned value is false, the change will be ignored.

But the code shows:

_stream = _stream.where((state) => !widget.ignoreChange(state));

Which means that changes are ignored if ignoreChange returns true [fitting with the naming].

This is a quick one-word PR that modifies the doc.

[codecov]

Codecov Report

Merging #62 into master will increase coverage by 0.07%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master      #62      +/-   ##
==========================================
+ Coverage   98.76%   98.83%   +0.07%     
==========================================
  Files           1        1              
  Lines          81       86       +5     
==========================================
+ Hits           80       85       +5     
  Misses          1        1

Impacted Files	Coverage Δ
lib/flutter_redux.dart	98.83% <ø> (+0.07%)	⬆️

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[brianegan]

Excellent, thanks! Sorry for the delay, was super busy the past few weeks and needed a bit of recovery time this week :)

I re-ran the tests (for some reason Travis timed out the first time) and everything is passing again. I'll publish an update with this change :)