Earlopain 7e8d94dec0 [DOC] Remove reference to F format specifier
There is no such thing:

```rb
irb(main):001> sprintf("%F", 123)
(irb):1:in 'Kernel#sprintf': malformed format string - %F (ArgumentError)
```
2026-05-18 23:16:37 +02:00
..
2026-02-06 18:35:02 -05:00
2026-02-21 14:17:24 -05:00