Document "normal" recovery after panic file usage...

[tomkrouper]

I was looking at #71 and wasn't sure if it made sense to have the error message that includes the normal recovery procedures. Or if in a panic, there is no normal recovery. Or if recovery is really so easy that basically it is just deleting the old file. If it is just a matter of, "In a normal recovery I would have deleted the _gst table and gone to have a beer." then this issue isn't needed. If there is more cleanup, then I think we should consider having something more than the, peace out ✌️ ❤️ message. (I may be paraphrasing you infinity more accurate error message in the PR.)

[shlomi-noach]

A cleanup would be:
drop table _tbl_gho;
drop table _tbl_ghc;
Names may change shortly. But basically these are the steps.

I think gh-ost should have a --cleaup flag, which is mutually exclusive to --alter. So either you're doing a migration, or you wish to cleanup.