feat(builder): min_value and required docs updated.

Fixes clap-rs#3259.

src/builder/arg.rs

@@ -1289,11 +1289,16 @@ impl<'help> Arg<'help> {
     /// `.min_values(2)`, and this argument would be satisfied if the user provided, 2 or more
     /// values.
     ///
-    /// **NOTE:** This does not implicitly set [`Arg::multiple_occurrences(true)`]. This is because
+    /// **NOTES:**
+    /// * This does not implicitly set [`Arg::multiple_occurrences(true)`]. This is because
     /// `-o val -o val` is multiple occurrences but a single value and `-o val1 val2` is a single
     /// occurrence with multiple values. For positional arguments this **does** set
     /// [`Arg::multiple_occurrences(true)`] because there is no way to determine the difference between multiple
     /// occurrences and multiple values.
+    /// * Passing a value of `1` is not the same as specifying [`Arg::required(true)`].
+    /// This is due to min and max validation only being performed for present arguments,
+    /// marking them as required will thus perform validation and a min value of 1
+    /// is unneccessary, ignored if not required.
     ///
     /// # Examples
     ///
@@ -1340,6 +1345,7 @@ impl<'help> Arg<'help> {
     /// assert_eq!(res.unwrap_err().kind(), ErrorKind::TooFewValues);
     /// ```
     /// [`Arg::multiple_occurrences(true)`]: Arg::multiple_occurrences()
+    /// [`Arg::required(true)`]: Arg::required()
     #[inline]
     #[must_use]
     pub fn min_values(mut self, qty: usize) -> Self {