Edit docs on consistency of PartialOrd and PartialEq

Use ordered list to make the information about implementations more readable.

library/core/src/cmp.rs

@@ -885,19 +885,18 @@ impl PartialOrd for Ordering {
 /// The `lt`, `le`, `gt`, and `ge` methods of this trait can be called using
 /// the `<`, `<=`, `>`, and `>=` operators, respectively.
 ///
-/// The methods of this trait must be consistent with each other and with those of `PartialEq` in
-/// the following sense:
-///
-/// - `a == b` if and only if `partial_cmp(a, b) == Some(Equal)`.
-/// - `a < b` if and only if `partial_cmp(a, b) == Some(Less)`
-///   (ensured by the default implementation).
-/// - `a > b` if and only if `partial_cmp(a, b) == Some(Greater)`
-///   (ensured by the default implementation).
-/// - `a <= b` if and only if `a < b || a == b`
-///   (ensured by the default implementation).
-/// - `a >= b` if and only if `a > b || a == b`
-///   (ensured by the default implementation).
-/// - `a != b` if and only if `!(a == b)` (already part of `PartialEq`).
+/// The methods of this trait must be consistent with each other and with those of [`PartialEq`].
+/// The following conditions must hold:
+///
+/// 1. `a == b` if and only if `partial_cmp(a, b) == Some(Equal)`.
+/// 2. `a < b` if and only if `partial_cmp(a, b) == Some(Less)`
+/// 3. `a > b` if and only if `partial_cmp(a, b) == Some(Greater)`
+/// 4. `a <= b` if and only if `a < b || a == b`
+/// 5. `a >= b` if and only if `a > b || a == b`
+/// 6. `a != b` if and only if `!(a == b)`.
+///
+/// Conditions 2–5 above are ensured by the default implementation.
+/// Condition 6 is already ensured by [`PartialEq`].
 ///
 /// If [`Ord`] is also implemented for `Self` and `Rhs`, it must also be consistent with
 /// `partial_cmp` (see the documentation of that trait for the exact requirements). It's