move the explanation of dict equal before its use

Author: Yzi-Li

Doc/library/stdtypes.rst

@@ -4838,6 +4838,28 @@ can be used interchangeably to index the same dictionary entry.
    Providing keyword arguments as in the first example only works for keys that
    are valid Python identifiers.  Otherwise, any valid keys can be used.
 
+   Dictionaries preserve insertion order.  Note that updating a key does not
+   affect the order.  Keys added after deletion are inserted at the end. ::
+
+      >>> d = {"one": 1, "two": 2, "three": 3, "four": 4}
+      >>> d
+      {'one': 1, 'two': 2, 'three': 3, 'four': 4}
+      >>> list(d)
+      ['one', 'two', 'three', 'four']
+      >>> list(d.values())
+      [1, 2, 3, 4]
+      >>> d["one"] = 42
+      >>> d
+      {'one': 42, 'two': 2, 'three': 3, 'four': 4}
+      >>> del d["two"]
+      >>> d["two"] = None
+      >>> d
+      {'one': 42, 'three': 3, 'four': 4, 'two': None}
+
+   .. versionchanged:: 3.7
+      Dictionary order is guaranteed to be insertion order.  This behavior was
+      an implementation detail of CPython from 3.6.
+
 
    These are the operations that dictionaries support (and therefore, custom
    mapping types should support too):
@@ -5012,28 +5034,6 @@ can be used interchangeably to index the same dictionary entry.
    value)`` pairs (regardless of ordering). Order comparisons ('<', '<=', '>=', '>') raise
    :exc:`TypeError`.
 
-   Dictionaries preserve insertion order.  Note that updating a key does not
-   affect the order.  Keys added after deletion are inserted at the end. ::
-
-      >>> d = {"one": 1, "two": 2, "three": 3, "four": 4}
-      >>> d
-      {'one': 1, 'two': 2, 'three': 3, 'four': 4}
-      >>> list(d)
-      ['one', 'two', 'three', 'four']
-      >>> list(d.values())
-      [1, 2, 3, 4]
-      >>> d["one"] = 42
-      >>> d
-      {'one': 42, 'two': 2, 'three': 3, 'four': 4}
-      >>> del d["two"]
-      >>> d["two"] = None
-      >>> d
-      {'one': 42, 'three': 3, 'four': 4, 'two': None}
-
-   .. versionchanged:: 3.7
-      Dictionary order is guaranteed to be insertion order.  This behavior was
-      an implementation detail of CPython from 3.6.
-
    Dictionaries and dictionary views are reversible. ::
 
       >>> d = {"one": 1, "two": 2, "three": 3, "four": 4}