pythongh-100428: Make int documentation more accurate

- Remove first link to lexical definition of integer literal, since it
  doesn't apply (differs in handling of leading zeros, base needs to be
  explicitly specified, unicode digits are allowed)
- Better describe handling of leading zeros and unicode digits
- Base 0 does not work exactly as like a code literal, since it allows
  Unicode digits. Link code literal to lexical definition of integer
  literal.

Author: hauntsaninja

Doc/library/functions.rst

@@ -890,17 +890,20 @@ are always available.  They are listed here in alphabetical order.
    For floating point numbers, this truncates towards zero.
 
    If *x* is not a number or if *base* is given, then *x* must be a string,
-   :class:`bytes`, or :class:`bytearray` instance representing an :ref:`integer
-   literal <integers>` in radix *base*.  Optionally, the literal can be
-   preceded by ``+`` or ``-`` (with no space in between) and surrounded by
-   whitespace.  A base-n literal consists of the digits 0 to n-1, with ``a``
+   :class:`bytes`, or :class:`bytearray` instance representing an integer
+   literal in radix *base*.  Optionally, the literal can be
+   preceded by ``+`` or ``-`` (with no space in between), have leading zeros,
+   or be surrounded by whitespace.
+
+   A base-n literal consists of Unicode digits representing 0 to n-1, with ``a``
    to ``z`` (or ``A`` to ``Z``) having
-   values 10 to 35.  The default *base* is 10. The allowed values are 0 and 2--36.
+   values 10 to 35.  The default *base* is 10. The allowed bases are 0 and 2--36.
    Base-2, -8, and -16 literals can be optionally prefixed with ``0b``/``0B``,
    ``0o``/``0O``, or ``0x``/``0X``, as with integer literals in code.  Base 0
-   means to interpret exactly as a code literal, so that the actual base is 2,
-   8, 10, or 16, and so that ``int('010', 0)`` is not legal, while
-   ``int('010')`` is, as well as ``int('010', 8)``.
+   means to interpret similar to a :ref:`code literal <integers>`, in that the
+   actual base is 2, 8, 10, or 16 as determined by the prefix. Base 0 also
+   disallows leading zeros: ``int('010', 0)`` is not legal, while ``int('010')``
+   and ``int('010', 8)`` are.
 
    The integer type is described in :ref:`typesnumeric`.