Update comment: *almost* every change needs a NEWS entry

[hugovk]

Bedevere's comment is slightly misleading (for example):

Every change to Python requires a NEWS entry.

Please, add it using the blurb_it Web app or the blurb command-line tool.

Bedevere's link to the devguide begins:

Almost all changes made to the code base deserve an entry in Misc/NEWS.d.

And then details the exceptions.

Let's update Bedevere's comment to say "Almost every change ..." instead of "Every change ...".

[JelleZijlstra]

See #439 for more alternative suggestions

[hugovk]

Updated following discussion in #439.

[codecov]

Codecov Report

Merging #447 (be58893) into master (77db0d5) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##            master      #447   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           18        18           
  Lines         1720      1720           
  Branches       208       208           
=========================================
  Hits          1720      1720           

Impacted Files	Coverage Δ
bedevere/news.py	100.00% <ø> (ø)