Add last updated column, purge stale

[Deleted user]

Manually purge all entries that haven't been updated for a year, to prevent accumulating stale data. Note this rule prominently at the top of the readme

[ocramz]

However I'd be careful in removing companies because they might still be using the language even if they don't advertise it in new job ads.

[erkmos]

I think purging after one year seems a bit harsh, it's not always possible to get first-hand accounts on whether they still use the language or not. It's an interesting idea though

[Deleted user]

Okay, it's been noted for consideration. I'll close for now.