Remove "optimization hints" section

I didn't feel like this section was pulling its weight. It also wasn't
entirely correct.

Author: ehuss

src/attributes/codegen.md

@@ -3,15 +3,6 @@ r[attributes.codegen]
 
 The following [attributes] are used for controlling code generation.
 
-r[attributes.codegen.hint]
-## Optimization hints
-
-r[attributes.codegen.hint.cold-inline]
-The `cold` and `inline` [attributes] give suggestions to generate code in a way that may be faster than what it would do without the hint. The attributes are only hints, and may be ignored.
-
-r[attributes.codegen.hint.usage]
-Both attributes can be used on [functions]. When applied to a function in a [trait], they apply only to that function when used as a default function for a trait implementation and not to all trait implementations. The attributes have no effect on a trait function without a body.
-
 r[attributes.codegen.inline]
 ### The `inline` attribute
 

src/items/functions.md

@@ -421,14 +421,15 @@ The attributes that have meaning on a function are:
 
 - [`cfg_attr`]
 - [`cfg`]
+- [`cold`]
 - [`deprecated`]
 - [`doc`]
 - [`export_name`]
+- [`inline`]
 - [`link_section`]
 - [`must_use`]
 - [`no_mangle`]
 - [Lint check attributes]
-- [Optimization hint attributes]
 - [Procedural macro attributes]
 - [Testing attributes]
 
@@ -483,7 +484,8 @@ fn foo_oof(#[some_inert_attribute] arg: u8) {
 [lint check attributes]: ../attributes/diagnostics.md#lint-check-attributes
 [procedural macro attributes]: ../procedural-macros.md#attribute-macros
 [testing attributes]: ../attributes/testing.md
-[optimization hint attributes]: ../attributes/codegen.md#optimization-hints
+[`cold`]: ../attributes/codegen.md#the-cold-attribute
+[`inline`]: ../attributes/codegen.md#the-inline-attribute
 [`deprecated`]: ../attributes/diagnostics.md#the-deprecated-attribute
 [`doc`]: ../../rustdoc/the-doc-attribute.html
 [`must_use`]: ../attributes/diagnostics.md#the-must_use-attribute