Add color to C-DOCS-RS. Fixes #76

Author: brson

README.md

@@ -1063,7 +1063,20 @@ Cargo.toml should contain a note next to the version to remember to bump the
 <a id="c-docs-rs"></a>
 ### Cargo.toml documentation key points to docs.rs (C-DOCS-RS)
 
-It should point to `"https://docs.rs/$crate"`.
+In most cases the `documentation` key in a crate's `Cargo.toml` should
+be `"https://docs.rs/$crate"`.
+
+[docs.rs] provides automatic hosting of crate documentation, with a
+consistent style, inter-crate navigation, and advanced features not
+included in the stock rustdoc output. It is a central destination for
+documentation of all Rust crates. Rust users are familiar with docs.rs
+and expect to go there for their API documentation. A crate that
+directs their users to a different site for its documentation will be
+noticably segregating itself from the larger portion of the
+ecosystem. This may be desirable to crate authors in some situations
+but should be considered carefully.
+
+[docs.rs]: https://docs.rs
 
 [C-RELNOTES]: #c-relnotes
 <a id="c-relnotes"></a>