Missing panic condition on API docs

[HeeillWang]

While I executed fuzzing, I faced some panics by expect. Though those are intentional crash, I think it's better to mention on docs as well. Some of APIs are already explicitly mention the panic condition.

I'll just list up the panic-condition-missing APIs, without reproduce condition as it's too obvious.

https://github.com/time-rs/time/blob/6248992b918638bc4f9e06e326c1fdace9c56fee/time/src/date.rs#L1304-L1307

https://github.com/time-rs/time/blob/6248992b918638bc4f9e06e326c1fdace9c56fee/time/src/duration.rs#L515-L535

https://github.com/time-rs/time/blob/6248992b918638bc4f9e06e326c1fdace9c56fee/time/src/duration.rs#L493-L513

https://github.com/time-rs/time/blob/6248992b918638bc4f9e06e326c1fdace9c56fee/time/src/duration.rs#L441-L453

[jhpratt]

Doc improvements are always welcome! It's not a priority for me at the moment.

[HeeillWang]

More cases :

https://github.com/time-rs/time/blob/c96bb1a4474b9af1289edbdf34514fbfe95fa833/time/src/duration.rs#L1311-L1314

https://github.com/time-rs/time/blob/c96bb1a4474b9af1289edbdf34514fbfe95fa833/time/src/duration.rs#L1266-L1269

https://github.com/time-rs/time/blob/c96bb1a4474b9af1289edbdf34514fbfe95fa833/time/src/ext.rs#L239-L279

[HeeillWang]

I'd like to defer adding doc for this at the moment, as I'm still running fuzzers, more cases may come out.

However, anyone is welcomed to create pr for this.

[jhpratt]

For panics that are deliberate, it's probably quickest to just check for assert! and .expect with ripgrep. Any other panics are likely unintentional — I can't think of any edge cases off the top of my head. .unwrap is not used anywhere, and this is enforced by clippy.