auto merge of #16428 : mdinger/rust/sort_attributes, r=cmr

Targetting at fixing most of #16414.

Sorts these alphabetically:
* [Crate-only attributes](http://doc.rust-lang.org/rust.html#crate-only-attributes)
* [Function-only attributes](http://doc.rust-lang.org/rust.html#function-only-attributes)
* [Miscellaneous attributes](http://doc.rust-lang.org/rust.html#miscellaneous-attributes)
* [Lint check attributes](http://doc.rust-lang.org/rust.html#lint-check-attributes)
* [Built-in Traits](http://doc.rust-lang.org/rust.html#built-in-traits)
* [Types](http://doc.rust-lang.org/rust.html#types)
* [Deriving](http://doc.rust-lang.org/rust.html#deriving)
* [Compiler Features](http://doc.rust-lang.org/rust.html#compiler-features)

Doesn't modify these:
* [Operators](http://doc.rust-lang.org/rust.html#operators): An alternative sorting is unclear.
* [Marker types](http://doc.rust-lang.org/rust.html#marker-types): Could be sorted but uncertain how. See below.
* [Stability](http://doc.rust-lang.org/rust.html#stability): Already sorted by stability

---

[Marker types](http://doc.rust-lang.org/rust.html#marker-types) has an extra newline above `fail_` which may throw off formatting (see #16412) or it may be for some other reason. If the newline is just a typo, I can just remove it and format this alphabetically like so:
```rust
// Sorted alphabetically
a_bread
b_bread
c_bread
fail_
fail_bounds_check
a_type
b_type
c_type
```

Marker types is listed as likely to become out of date so I don't know if this is worth doing anyway.

[EDIT] modified `Marker types` now and tried to update the language items list.

diff --cc src/doc/rust.md
Simple merge