docs: Clarify PossibleValue is likely not needed

Fixes #4504

src/builder/possible_value.rs

@@ -7,8 +7,11 @@ use crate::util::eq_ignore_case;
 ///
 /// This is used for specifying [possible values] of [Args].
 ///
-/// **NOTE:** This struct is likely not needed for most usecases as it is only required to
-/// [hide] single values from help messages and shell completions or to attach [help] to possible values.
+/// See also [`PossibleValuesParser`][crate::builder::PossibleValuesParser]
+///
+/// **NOTE:** Most likely you can use strings, rather than `PossibleValue` as it is only required
+/// to [hide] single values from help messages and shell completions or to attach [help] to
+/// possible values.
 ///
 /// # Examples
 ///
@@ -23,6 +26,7 @@ use crate::util::eq_ignore_case;
 ///         PossibleValue::new("secret speed").hide(true)
 ///     ]);
 /// ```
+///
 /// [Args]: crate::Arg
 /// [possible values]: crate::builder::ValueParser::possible_values
 /// [hide]: PossibleValue::hide()

src/builder/value_parser.rs

@@ -1066,8 +1066,9 @@ impl<E: crate::ValueEnum + Clone + Send + Sync + 'static> Default for EnumValueP
 /// Verify the value is from an enumerated set of [`PossibleValue`][crate::builder::PossibleValue].
 ///
 /// See also:
-/// - [`EnumValueParser`] for directly supporting `enum`s
-/// - [`TypedValueParser::map`] for adapting values to a more specialized type
+/// - [`EnumValueParser`] for directly supporting [`ValueEnum`][crate::ValueEnum] types
+/// - [`TypedValueParser::map`] for adapting values to a more specialized type, like an external
+///   enums that can't implement [`ValueEnum`][crate::ValueEnum]
 ///
 /// # Example
 ///