Singularize "the rest pattern"

Like "the wildcard pattern", there is only one "rest pattern".  Let's
singularize this and add the appropriate redirect.

Author: traviscross

book.toml

@@ -35,6 +35,7 @@ use-boolean-and = true
 "/items/traits.html#object-safety" = "traits.html#dyn-compatibility"
 "/lifetime-elision.html#static-lifetime-elision" = "lifetime-elision.html#const-and-static-elision"
 "/macros-by-example.html#path-based-scope" = "macros-by-example.html#the-macro_export-attribute"
+"/patterns.html#rest-patterns" = "patterns.html#rest-pattern"
 "/procedural-macros.html#attribute-macros" = "procedural-macros.html#the-proc_macro_attribute-attribute"
 "/procedural-macros.html#derive-macros" = "procedural-macros.html#the-proc_macro_derive-attribute"
 "/procedural-macros.html#function-like-procedural-macros" = "procedural-macros.html#the-proc_macro-attribute"

src/patterns.md

@@ -93,7 +93,7 @@ Destructuring breaks up a value into its component pieces.
 The syntax used is almost the same as when creating such values.
 
 r[patterns.destructure.wildcard]
-In a pattern whose [scrutinee] expression has a `struct`, `enum` or `tuple` type, a [wildcard pattern](#wildcard-pattern) (`_`) stands in for a *single* data field, whereas an [et cetera](#grammar-StructPatternEtCetera) or [rest pattern](#rest-patterns) (`..`) stands in for *all* the remaining fields of a particular variant.
+In a pattern whose [scrutinee] expression has a `struct`, `enum` or `tuple` type, a [wildcard pattern](#wildcard-pattern) (`_`) stands in for a *single* data field, whereas an [et cetera](#grammar-StructPatternEtCetera) or [rest pattern][patterns.rest] (`..`) stands in for *all* the remaining fields of a particular variant.
 
 r[patterns.destructure.named-field-shorthand]
 When destructuring a data structure with named (but not numbered) fields, it is allowed to write `fieldname` as a shorthand for `fieldname: fieldname`.
@@ -421,7 +421,7 @@ r[patterns.wildcard.refutable]
 The wildcard pattern is always irrefutable.
 
 r[patterns.rest]
-## Rest patterns
+## Rest pattern
 
 r[patterns.rest.syntax]
 ```grammar,patterns
@@ -470,7 +470,8 @@ if let [.., penultimate, _] = slice {
 }
 
 # let tuple = (1, 2, 3, 4, 5);
-// Rest patterns may also be used in tuple and tuple struct patterns.
+// The rest pattern may also be used in tuple and tuple
+// struct patterns.
 match tuple {
     (1, .., y, z) => println!("y={} z={}", y, z),
     (.., 5) => println!("tail must be 5"),
@@ -974,7 +975,7 @@ r[patterns.slice.refutable-array]
 Slice patterns are irrefutable when matching an array as long as each element is irrefutable.
 
 r[patterns.slice.refutable-slice]
-When matching a slice, it is irrefutable only in the form with a single `..` [rest pattern](#rest-patterns) or [identifier pattern](#identifier-patterns) with the `..` rest pattern as a subpattern.
+When matching a slice, it is irrefutable only in the form with a single `..` [rest pattern][patterns.rest] or [identifier pattern](#identifier-patterns) with the `..` rest pattern as a subpattern.
 
 r[patterns.slice.restriction]
 Within a slice, a range pattern without both lower and upper bound must be enclosed in parentheses, as in `(a..)`, to clarify it is intended to match against a single slice element.

src/syntax-index.md

@@ -100,7 +100,7 @@ This appendix provides an index of tokens and common forms with links to where t
 | `<=`   | Le          | [less than or equal to][comparison] |
 | `@`    | At          | [subpattern binding] |
 | `.`    | Dot         | [field access][field], [tuple index] |
-| `..`   | DotDot      | [range expressions][expr.range], [struct expressions], [rest patterns], [range patterns], [struct patterns] |
+| `..`   | DotDot      | [range expressions][expr.range], [struct expressions], [rest pattern], [range patterns], [struct patterns] |
 | `...`  | DotDotDot   | [variadic functions], [range patterns] |
 | `..=`  | DotDotEq    | [inclusive range expressions][expr.range], [range patterns] |
 | `,`    | Comma       | various separators |
@@ -258,7 +258,7 @@ This appendix provides an index of tokens and common forms with links to where t
 | `"foo"`, `'a'`, `123`, `2.4`, …   | [literal patterns] |
 | `ident`                           | [identifier patterns] |
 | `_`                               | [wildcard pattern] |
-| `..`                              | [rest patterns] |
+| `..`                              | [rest pattern] |
 | `..`, `a..`, `..b`, `a..b`, `a..=b`, `..=b` | [range patterns] |
 | `&pattern`<br>`&mut pattern`      | [reference patterns] |
 | `path {…}`                        | [struct patterns] |
@@ -403,7 +403,7 @@ This appendix provides an index of tokens and common forms with links to where t
 [relaxed trait bounds]: bound.sized
 [repeat array expressions]: expr.array
 [reserved keyword]: lex.keywords.reserved
-[rest patterns]: patterns.rest
+[rest pattern]: patterns.rest
 [return expressions]: expr.return
 [self parameters]: items.fn.params.self-pat
 [single-element tuple expressions]: expr.tuple