Consistently use sentence case

Part of our style guide is to use sentence case for headings. The
Reference was very inconsistent with this. This updates all the headings
to use sentence case.

Author: ehuss

CONTRIBUTING.md

@@ -32,7 +32,7 @@ we welcome PRs to fix them. Additionally, larger editing jobs that help remove
 the number of parentheticals, remove comma splices, italicize term definitions
 and other similar tasks are helpful.
 
-## Adding Examples and Glossary Entries
+## Adding examples and glossary entries
 
 Examples are great. Many people will only read examples and ignore the prose.
 Ideally, every facet of every feature will have an example.
@@ -41,7 +41,7 @@ Likewise, the reference has a glossary. It doesn't need to explain every facet
 of every feature nor contain every definition, but it does need to be expanded
 upon. Ideally entries in the glossary link to the associated documentation.
 
-## Adding Documentation
+## Adding documentation
 
 There are a lot of features that are not documented at all or are documented
 poorly. This is the hardest, but definitely most valuable. Pick an unassigned

docs/review-policy.md

@@ -17,7 +17,7 @@ Team members are given permission to merge changes from other contributors in th
 - Minor changes to the tooling may be made with a review from a team member. This includes bug fixes, minor additions that are unlikely to have objections, and additions that have already been discussed.
 - Major changes, such as a change in how content is authored, or major changes to how the tooling works should be approved by the team without blocking objections.
 
-## Review Process Flowchart
+## Review process flowchart
 
 When reviewing a pull request, ask yourself the following questions:
 
@@ -44,4 +44,4 @@ Some PRs are right but are awkwardly worded or have typographical problems. If t
 <!-- TODO -->
 This policy does not yet cover the process for getting final approval from the relevant teams.
 
-[authoring guide]: authoring.md
+[authoring guide]: authoring.md

src/SUMMARY.md

@@ -13,8 +13,8 @@
     - [Tokens](tokens.md)
 
 - [Macros](macros.md)
-    - [Macros By Example](macros-by-example.md)
-    - [Procedural Macros](procedural-macros.md)
+    - [Macros by example](macros-by-example.md)
+    - [Procedural macros](procedural-macros.md)
 
 - [Crates and source files](crates-and-source-files.md)
 
@@ -35,15 +35,15 @@
     - [Implementations](items/implementations.md)
     - [External blocks](items/external-blocks.md)
     - [Generic parameters](items/generics.md)
-    - [Associated Items](items/associated-items.md)
+    - [Associated items](items/associated-items.md)
 
 - [Attributes](attributes.md)
     - [Testing](attributes/testing.md)
     - [Derive](attributes/derive.md)
     - [Diagnostics](attributes/diagnostics.md)
     - [Code generation](attributes/codegen.md)
     - [Limits](attributes/limits.md)
-    - [Type System](attributes/type_system.md)
+    - [Type system](attributes/type_system.md)
     - [Debugger](attributes/debugger.md)
 
 - [Statements and expressions](statements-and-expressions.md)
@@ -91,10 +91,10 @@
         - [Impl trait type](types/impl-trait.md)
         - [Type parameters](types/parameters.md)
         - [Inferred type](types/inferred.md)
-    - [Dynamically Sized Types](dynamically-sized-types.md)
+    - [Dynamically sized types](dynamically-sized-types.md)
     - [Type layout](type-layout.md)
     - [Interior mutability](interior-mutability.md)
-    - [Subtyping and Variance](subtyping.md)
+    - [Subtyping and variance](subtyping.md)
     - [Trait and lifetime bounds](trait-bounds.md)
     - [Type coercions](type-coercions.md)
     - [Destructors](destructors.md)
@@ -125,15 +125,15 @@
     - [Behavior considered undefined](behavior-considered-undefined.md)
     - [Behavior not considered unsafe](behavior-not-considered-unsafe.md)
 
-- [Constant Evaluation](const_eval.md)
+- [Constant evaluation](const_eval.md)
 
-- [Application Binary Interface](abi.md)
+- [Application binary interface](abi.md)
 
 - [The Rust runtime](runtime.md)
 
 - [Appendices](appendices.md)
     - [Grammar summary](grammar.md)
-    - [Macro Follow-Set Ambiguity Formal Specification](macro-ambiguity.md)
+    - [Macro follow-set ambiguity formal specification](macro-ambiguity.md)
     - [Influences](influences.md)
     - [Test summary](test-summary.md)
     - [Glossary](glossary.md)

src/abi.md

@@ -1,5 +1,5 @@
 r[abi]
-# Application Binary Interface (ABI)
+# Application binary interface (ABI)
 
 r[abi.intro]
 This section documents features that affect the ABI of the compiled output of

src/attributes.md

@@ -107,7 +107,7 @@ fn some_unused_variables() {
 ```
 
 r[attributes.meta]
-## Meta Item Attribute Syntax
+## Meta item attribute syntax
 
 r[attributes.meta.intro]
 A "meta item" is the syntax used for the [Attr] rule by most [built-in

src/attributes/diagnostics.md

@@ -102,7 +102,7 @@ pub mod m3 {
 > `rustc` allows setting lint levels on the [command-line][rustc-lint-cli], and also supports [setting caps][rustc-lint-caps] on the lints that are reported.
 
 r[attributes.diagnostics.lint.reason]
-### Lint Reasons
+### Lint reasons
 
 All lint attributes support an additional `reason` parameter, to give context why
 a certain attribute was added. This reason will be displayed as part of the lint

src/conditional-compilation.md

@@ -71,7 +71,7 @@ r[cfg.option-key-uniqueness]
 Keys do not need to be unique. For example, both `feature = "std"` and `feature = "serde"` can be set at the same time.
 
 r[cfg.options.set]
-## Set Configuration Options
+## Set configuration options
 
 r[cfg.options.general]
 Which configuration options are set is determined statically during the

src/crates-and-source-files.md

@@ -75,7 +75,7 @@ apply to the crate as a whole.
 ```
 
 r[crate.main]
-## Main Functions
+## Main functions
 
 r[crate.main.general]
 A crate that contains a `main` [function] can be compiled to an executable.

src/dynamically-sized-types.md

@@ -1,5 +1,5 @@
 r[dynamic-sized]
-# Dynamically Sized Types
+# Dynamically sized types
 
 r[dynamic-sized.intro]
 Most types have a fixed size that is known at compile time and implement the trait [`Sized`][sized]. A type with a size that is known only at run-time is called a _dynamically sized type_ (_DST_) or, informally, an unsized type.  [Slices], [trait objects], and [str] are examples of <abbr title="dynamically sized types">DSTs</abbr>.

src/expressions.md

@@ -147,7 +147,7 @@ assert_eq!(
 > Since this is applied recursively, these expressions are also evaluated from innermost to outermost, ignoring siblings until there are no inner subexpressions.
 
 r[expr.place-value]
-## Place Expressions and Value Expressions
+## Place expressions and value expressions
 
 r[expr.place-value.intro]
 Expressions are divided into two main categories: place expressions and value expressions;
@@ -334,7 +334,7 @@ x; // OK
 ```
 
 r[expr.implicit-borrow]
-### Implicit Borrows
+### Implicit borrows
 
 r[expr.implicit-borrow-intro]
 Certain expressions will treat an expression as a place expression by implicitly borrowing it.
@@ -366,13 +366,13 @@ Implicit borrows may be taken in the following expressions:
 * Arguments to [`format_args!`] except the format string.
 
 r[expr.overload]
-## Overloading Traits
+## Overloading traits
 
 Many of the following operators and expressions can also be overloaded for other types using traits in `std::ops` or `std::cmp`.
 These traits also exist in `core::ops` and `core::cmp` with the same names.
 
 r[expr.attr]
-## Expression Attributes
+## Expression attributes
 
 r[expr.attr.restriction]
 [Outer attributes] before an expression are allowed only in a few specific cases: