Update two URLs and fix a typo

src/linkage.md

@@ -10,7 +10,7 @@ statically and dynamically. This section will explore the various methods to
 link crates together, and more information about native libraries can be
 found in the [FFI section of the book][ffi].
 
-[ffi]: ../book/ch19-01-unsafe-rust.html#using-extern-functions-to-call-external-code
+[ffi]: ../book/ch20-01-unsafe-rust.html#using-extern-functions-to-call-external-code
 
 r[link.type]
 In one session of compilation, the compiler can generate multiple artifacts

src/tokens.md

@@ -869,7 +869,7 @@ r[lex.token.reserved-guards.edition2024]
 [Integer literal expressions]: expressions/literal-expr.md#integer-literal-expressions
 [keywords]: keywords.md
 [literal expressions]: expressions/literal-expr.md
-[loop labels]: expressions/loop-expr.md
+[loop labels]: expressions/loop-expr.md#loop-labels
 [macros]: macros-by-example.md
 [String continuation escapes]: expressions/literal-expr.md#string-continuation-escapes
 [syntax index]: syntax-index.md#operators-and-punctuation

src/types/textual.md

@@ -8,7 +8,7 @@ r[type.text.char-value]
 A value of type `char` is a [Unicode scalar value] (i.e. a code point that is not a surrogate), represented as a 32-bit unsigned word in the 0x0000 to 0xD7FF or 0xE000 to 0x10FFFF range.
 
 r[type.text.char-precondition]
-It is immediate [undefined behavior] to create a `char` that falls outside this range. A `[char]` is effectively a UCS-4 / UTF-32 string of length 1.
+It is immediate [undefined behavior] to create a `char` that falls outside this range. A `char` is effectively a UCS-4 / UTF-32 string of length 1.
 
 r[type.text.str-value]
 A value of type `str` is represented the same way as `[u8]`, a slice of 8-bit unsigned bytes. However, the Rust standard library makes extra assumptions about `str`: methods working on `str` assume and ensure that the data in there is valid UTF-8. Calling a `str` method with a non-UTF-8 buffer can cause [undefined behavior] now or in the future.