editorial tweaks

- Removes specification of `if let` guards' bindings "only" being valid
if the guard succeeds. The arm body is only executed if the guard
succeeds, so the bindings are always usable within the arm body when
it's executed.

- Makes terminology slightly more consistent (replaces some remaining
uses of "`if let` guard" with "`let` pattern")

- Other small wording and punctuation tweaks.

Author: dianne

src/expressions/match-expr.md

@@ -166,10 +166,9 @@ r[expr.match.guard.let]
 Guards can use `let` patterns to conditionally match a scrutinee and to bind new variables into scope when the pattern matches successfully.
 
 > [!EXAMPLE]
-> In this example, the guard condition `let Some(first_char) = name.chars().next()` is evaluated. If the `if let` expression successfully matches (i.e., the string has at least one character), the arm's body is executed with both `name` and `first_char` available. Otherwise, pattern matching continues to the next arm.
->
-> The key point is that the `if let` guard creates a new binding (`first_char`) that's only available if the guard succeeds, and this binding can be used alongside the original pattern bindings (`name`) in the arm's body.
+> In this example, the guard condition `let Some(first_char) = name.chars().next()` is evaluated. If the `let` pattern successfully matches (i.e. the string has at least one character), the arm's body is executed. Otherwise, pattern matching continues to the next arm.
 >
+> The `let` pattern creates a new binding (`first_char`), which can be used alongside the original pattern bindings (`name`) in the arm's body.
 > ```rust
 > # enum Command {
 > #     Run(String),

src/names/scopes.md

@@ -49,7 +49,7 @@ r[names.scopes.pattern-bindings.let-chains]
 r[names.scopes.pattern-bindings.match-arm]
 * [`match` arms] bindings are within the [match guard] and the match arm expression.
 r[names.scopes.pattern-bindings.match-guard-let]
-* [`match` guard `let`] bindings are valid in the following guard conditions and the match arm expression if the guard succeeds.
+* [`match` guard `let`] bindings are valid in the following guard conditions and the match arm expression.
 
 r[names.scopes.pattern-bindings.items]
 Local variable scopes do not extend into item declarations.