nils caae551ecb
Rollup merge of #106434 - clubby789:document-sum-result, r=the8472
Document `Iterator::sum/product` for Option/Result

Closes #105266

We already document the similar behavior for `collect()` so I believe it makes sense to add this too. The Option/Result implementations *are* documented on their respective pages and the page for `Sum`, but buried amongst many other trait impls which doesn't make it very discoverable.

`````@rustbot````` label +A-docs
2023-03-21 13:00:21 +01:00
..