Document how to disable caching rewritten .pyc files to disk
Document how to disable caching rewritten .pyc files to disk

Also changed how the section is presented: instead of "Note" blocks, use proper
sections as those contain enough information to exist on their own.

Fix #1680

tomviner/pytest,alfredodeza/pytest,markshao/pytest,RonnyPfannschmidt/pytest,pytest-dev/pytest,The-Compiler/pytest,The-Compiler/pytest,nicoddemus/pytest,tomviner/pytest,Akasurde/pytest,nicoddemus/pytest