docs - now (#29182)

docs/questions/query-builder/expressions-list.md

docs/questions/query-builder/expressions/converttimezone.md

docs/questions/query-builder/expressions/datetimeadd.md

docs/questions/query-builder/expressions/datetimediff.md

docs/questions/query-builder/expressions/datetimesubtract.md

docs/questions/query-builder/expressions/now.md