`docify::embed_diff`

[kianenigma]

#![doc = docify::embed_diff("file_path.rs", item_1, item_2)]

There must be good diff libs for rust, and the rest is more or less simple, I presume. We read the two excerpts, pass them to the fn diff(a, b), which I presume would return some sort of diff-style string, and use that.

How crazy is this?

cc @shawntabrizi