[general issue] Add docs for re-running initC: no BSEDict

[katiebreivik]

We should have a docs page that gives people a direct example for rerunning initC and BSEDict = {}. Also check warnings for if an initC with pre-evolved columns, warn for BSEDict overwrite.

@TomWagg here's the issue.

[fgeeuu3u3u]

i want to know how to resolve this warnning