Fix small typo in init.md (#1277)

Co-authored-by: Hynek Schlawack <hs@ox.cx>

docs/init.md

@@ -262,7 +262,7 @@ C(x=128)
 >>> C("128")
 Traceback (most recent call last):
    ...
-TypeError: ("'x' must be <class 'int'> (got '128' that is a <class 'str'>).", Attribute(name='x', default=NOTHING, validator=[<instance_of validator for type <class 'int'>>, <function fits_byte at 0x10fd7a0d0>], repr=True, cmp=True, hash=True, init=True, metadata=mappingproxy({}), type=None, converter=one), <class 'int'>, '128')
+TypeError: ("'x' must be <class 'int'> (got '128' that is a <class 'str'>).", Attribute(name='x', default=NOTHING, validator=[<instance_of validator for type <class 'int'>>, <function fits_byte at 0x10fd7a0d0>], repr=True, cmp=True, hash=True, init=True, metadata=mappingproxy({}), type=None, converter=None), <class 'int'>, '128')
 >>> C(256)
 Traceback (most recent call last):
    ...