Tox entry point to lint docstrings
Tox entry point to lint docstrings

pep257 define a standard for docstrings.  The linter is available as a
flake8 extension 'flake8-docstrings'.

Hack in the flake8 command to only include errors starting with D.

Usage:

  tox -e flake8-docstrings

Change-Id: If8b5788aee1e64db8accead39c3058057874932b

smalyshev/pywikibot-core,hasteur/g13bot_tools_new,VcamX/pywikibot-core,PersianWikipedia/pywikibot-core,icyflame/batman,Darkdadaah/pywikibot-core,jayvdb/pywikibot-core,emijrp/pywikibot-core,hasteur/g13bot_tools_new,magul/pywikibot-core,xZise/pywikibot-core,wikimedia/pywikibot-core,trishnaguha/pywikibot-core,TridevGuha/pywikibot-core,npdoty/pywikibot,wikimedia/pywikibot-core,darthbhyrava/pywikibot-local,happy5214/pywikibot-core,h4ck3rm1k3/pywikibot-core,magul/pywikibot-core,valhallasw/pywikibot-core,happy5214/pywikibot-core,jayvdb/pywikibot-core,npdoty/pywikibot,h4ck3rm1k3/pywikibot-core,Darkdadaah/pywikibot-core,hasteur/g13bot_tools_new