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 proc-macro2'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.

Author: dtolnay

Cargo.toml

@@ -37,6 +37,9 @@ span-locations = []
 # This feature no longer means anything.
 nightly = []
 
+[lib]
+doc-scrape-examples = false
+
 [workspace]
 members = ["benches/bench-libproc-macro", "tests/ui"]