documenting how to point pytest at local code
documenting how to point pytest at local code

Related to #1937
MichaelAquilina/pytest,jaraco/pytest,tomviner/pytest,markshao/pytest,ddboline/pytest,The-Compiler/pytest,nicoddemus/pytest,tgoodlet/pytest,The-Compiler/pytest,nicoddemus/pytest,pytest-dev/pytest,hackebrot/pytest,tomviner/pytest,skylarjhdownes/pytest,txomon/pytest,tareqalayan/pytest,alfredodeza/pytest,flub/pytest,rmfitzpatrick/pytest,pfctdayelise/pytest,Akasurde/pytest,davidszotten/pytest,RonnyPfannschmidt/pytest