Rollup merge of #36099 - skade:better-try-documentation, r=steveklabnik
Rollup merge of #36099 - skade:better-try-documentation, r=steveklabnik

Document try!'s error conversion behaviour

try!'s documentation currently doesn't document the error conversion behaviour of the macro. This patch extends the documentation.

Open questions:
* is it worthwhile to have seperate examples with and without wrapping behaviour? It's not immediately obvious that From<T> for T is always defined. Though this is necessary for the macro to work in any case, is this the place to expect that knowledge.

graydon/rust,aidancully/rust,aidancully/rust,GBGamer/rust,GBGamer/rust,GBGamer/rust,GBGamer/rust,graydon/rust,graydon/rust,GBGamer/rust,GBGamer/rust,GBGamer/rust,GBGamer/rust,graydon/rust,aidancully/rust,graydon/rust,aidancully/rust,aidancully/rust,graydon/rust,aidancully/rust