Revert "replace code with pre"

This reverts commit 570eeea8db28b43b2ac5022fe4f757eae9230b12.
Revert "update code section"

This reverts commit 288ca6347c1fc4271520a6cd3282601b7dbcada9.
Revert "trying out html support in markdown"

This reverts commit d98b8cfcd9efb95c8decd3fdc284321a99a44a3a.