Fix some doc comments (#750)

These were triggering a stack overflow in dartdoc, and regardless, should probably have been in backticks.

lib/src/collection/multimap.dart

@@ -23,9 +23,10 @@ abstract class Multimap<K, V> {
  /// Constructs a new list-backed multimap.
  factory Multimap() => ListMultimap<K, V>();
 
- /// Constructs a new list-backed multimap. For each element e of [iterable],
- /// adds an association from [key](e) to [value](e). [key] and [value] each
- /// default to the identity function.
+ /// Constructs a new list-backed multimap.
+ ///
+ /// For each element `e` of [iterable], adds an association from `key(e)` to
+ /// `value(e)`. [key] and [value] each default to the identity function.
  factory Multimap.fromIterable(Iterable iterable,
  {K Function(dynamic)? key,
  V Function(dynamic)? value}) = ListMultimap<K, V>.fromIterable;
@@ -243,9 +244,10 @@ abstract class _BaseMultimap<K, V, C extends Iterable<V>>
 class ListMultimap<K, V> extends _BaseMultimap<K, V, List<V>> {
  ListMultimap();
 
- /// Constructs a new list-backed multimap. For each element e of [iterable],
- /// adds an association from [key](e) to [value](e). [key] and [value] each
- /// default to the identity function.
+ /// Constructs a new list-backed multimap.
+ ///
+ /// For each element `e` of [iterable], adds an association from `key(e)` to
+ /// `value(e)`. [key] and [value] each default to the identity function.
  ListMultimap.fromIterable(super.iterable, {super.key, super.value})
  : super.fromIterable();
 
@@ -285,9 +287,10 @@ class ListMultimap<K, V> extends _BaseMultimap<K, V, List<V>> {
 class SetMultimap<K, V> extends _BaseMultimap<K, V, Set<V>> {
  SetMultimap();
 
- /// Constructs a new set-backed multimap. For each element e of [iterable],
- /// adds an association from [key](e) to [value](e). [key] and [value] each
- /// default to the identity function.
+ /// Constructs a new set-backed multimap.
+ ///
+ /// For each element `e` of [iterable], adds an association from `key(e)` to
+ /// `value(e)`. [key] and [value] each default to the identity function.
  SetMultimap.fromIterable(super.iterable, {super.key, super.value})
  : super.fromIterable();
 

lib/testing/src/async/fake_async.dart

@@ -27,7 +27,7 @@ import 'package:quiver/time.dart';
 /// simulated using [elapseBlocking].
 ///
 /// To allow the unit under test to tell time, it can receive a [Clock] as a
-/// dependency, and default it to [const Clock()] in production, but then use
+/// dependency, and default it to `const Clock()` in production, but then use
 /// [Clock] in test code.
 ///
 /// Example: