Change all mentions of doc to docid
Change all mentions of doc to docid

In hindsight, the variable name "doc" implies we are manipulating the
document itself when, in reality, we are manipulating the index of the
document. "docid" better expresses this concept.

AWPorter/aima-python,AmberJBlue/aima-python,WmHHooper/aima-python,JoeLaMartina/AlphametricProject,SimeonFritz/aima-python,reachtarunhere/aima-python,SeanCameronConklin/aima-python,WhittKinley/aima-python,Chipe1/aima-python,austinban/aima-python,WhittKinley/ConnectProject,chandlercr/aima-python,SeanCameronConklin/aima-python,reachtarunhere/aima-python,SimeonFritz/aima-python,JoeLaMartina/aima-python,JoeLaMartina/AlphametricProject,austinban/aima-python,chandlercr/aima-python,SeanCameronConklin/aima-python,jottenlips/aima-python,jo-tez/aima-python,AWPorter/aima-python,grantvk/aima-python,phaller0513/aima-python,armadill-odyssey/aima-python,AmberJBlue/aima-python,sofmonk/aima-python,phaller0513/aima-python,zayneanderson/aima-python,Fruit-Snacks/aima-python,NolanBecker/aima-python,aimacode/aima-python,AmberJBlue/aima-python,grantvk/aima-python,WmHHooper/aima-python,zayneanderson/aima-python,NolanBecker/aima-python,sofmonk/aima-python,WmHHooper/aima-python,JoeLaMartina/aima-python,grantvk/aima-python,SimeonFritz/aima-python,jottenlips/aima-python,chandlercr/aima-python,phaller0513/aima-python,NolanBecker/aima-python,austinban/aima-python,JamesDickenson/aima-python,willhess/aima-python,WhittKinley/aima-python,SnShine/aima-python,Fruit-Snacks/aima-python,aimacode/aima-python,abbeymiles/aima-python,JoeLaMartina/aima-python,JamesDickenson/aima-python,JamesDickenson/aima-python,armadill-odyssey/aima-python,willhess/aima-python,armadill-odyssey/aima-python,jo-tez/aima-python,willhess/aima-python,Chipe1/aima-python,WhittKinley/aima-python,Fruit-Snacks/aima-python,abbeymiles/aima-python,JoeLaMartina/AlphametricProject,WhittKinley/ConnectProject,WhittKinley/ConnectProject,SnShine/aima-python,AWPorter/aima-python,WmHHooper/aima-python,zayneanderson/aima-python,jottenlips/aima-python,abbeymiles/aima-python