Opt out -Zrustdoc-scrape-examples on docs.rs

I'd like a chance to audit all the code that rustdoc is inserting into
the docs. Currently I am skeptical that showing syn's internal usages of
APIs is a net benefit to the public documentation. I am also skeptical
that quite so many examples are needed, and that they should be featured
so prominently in comparison to handwritten docs. Lastly I wish there
were a way to turn this behavior off on a more granular basis.

Cargo.toml

@@ -54,6 +54,9 @@ tar = "0.4.16"
 termcolor = "1.0"
 walkdir = "2.1"
 
+[lib]
+doc-scrape-examples = false
+
 [[bench]]
 name = "rust"
 harness = false