docs: fix incorrect incorrect links/typos across `tracing`

[davidbarsky]

While researching tracing ecosystem, I found a lot of similar typos. Here are some of them:

• https://docs.rs/tracing/0.1.40/tracing/attr.instrument.html (in addition to already mentioned std::fmt::Debug problem, this page contains similarly broken mentions of Result::Ok, std::fmt::Debug [yes, another mention!], std::fmt::Display, Result::Ok [again], Result::Err)
• https://docs.rs/tracing/0.1.40/tracing/trait.Subscriber.html#impl-dyn+Subscriber+%2B+Sync : [Subscriber]
• https://docs.rs/tracing-forest/0.1.6/tracing_forest/struct.ForestLayer.html#impl-Layer%3CS%3E-for-ForestLayer%3CP,+T%3E : [Subscriber]
• https://docs.rs/tracing-serde/0.1.3/tracing_serde/#unstable-features : [Visit::record_value]
• https://docs.rs/tracing-subscriber/0.3.17/tracing_subscriber/fmt/fn.fmt.html : [SubscriberBuilder::default()]
• https://docs.rs/tracing-subscriber/0.3.17/tracing_subscriber/fmt/format/index.html#functions : "[event formatter]" two times
• https://docs.rs/tracing-subscriber/0.3.17/tracing_subscriber/fmt/index.html#functions : "[event formatter]"
• https://docs.rs/tracing-tree/0.2.5/tracing_tree/time/trait.FormatTime.html : "[LocalDateTime]" two times

So, something goes wrong here. It seems we need to do some automatic search-and-replace

Originally posted by @safinaskar in https://github.com/tokio-rs/tracing/issues/2775#issuecomment-1786028644

[kaffarell]

Hi! Submitted a PR for this (#2785)...

1. https://docs.rs/tracing/0.1.40/tracing/attr.instrument.html (in addition to already mentioned std::fmt::Debug problem, this page contains similarly broken mentions of Result::Ok, std::fmt::Debug [yes, another mention!], std::fmt::Display, Result::Ok [again], Result::Err) - Fixed this
2. https://docs.rs/tracing/0.1.40/tracing/trait.Subscriber.html#impl-dyn+Subscriber+%2B+Sync : [Subscriber] - Already fixed on master (Subscriber has been renamed to Collector as well)
3. https://docs.rs/tracing-forest/0.1.6/tracing_forest/struct.ForestLayer.html#impl-Layer%3CS%3E-for-ForestLayer%3CP,+T%3E - Not part of tracing
4. https://docs.rs/tracing-serde/0.1.3/tracing_serde/#unstable-features : [Visit::record_value] - already fixed on master
5. https://docs.rs/tracing-subscriber/0.3.17/tracing_subscriber/fmt/fn.fmt.html : [SubscriberBuilder::default()] - already fixed on master (and renamed to CollectorBuilder)
6. https://docs.rs/tracing-subscriber/0.3.17/tracing_subscriber/fmt/format/index.html#functions : "[event formatter]" two times - already fixed on master
7. https://docs.rs/tracing-subscriber/0.3.17/tracing_subscriber/fmt/index.html#functions : "[event formatter]" - same as before
8. https://docs.rs/tracing-tree/0.2.5/tracing_tree/time/trait.FormatTime.html : "[LocalDateTime]" two times - not part of the tracing core

LMK if you want to backport some of these to v0.1.x (Although I don't think its worth).