Add column path KDoc. #1069
Description
Sometimes column selection DSL is not enough (for example in move, when you want to move column into a new path not existing yet). And it's not that obvious. Example:
df.move { age and weight }.into { pathOf("info", it.name()) }
df.move { age and weight }.into { "info"[it.name()] }
Should be added in move/into Kdoc (#813).