Update thebroke RST markup in items() method docstrings (#1299)

## Summary

Fix malformed RST markup in the `items()` docstrings of `MultiDict` and
`MultiDictProxy`.

The original text `*(key, value) pairs)` has been present since the
initial commit (f84e6bc). It has an unmatched `*` (opening RST emphasis
with no closing `*`) and an extra trailing `)`. Changed to `((key,
value) pairs)` to use plain parentheses matching the tuple notation.


Co-authored-by: Sam Bull <[email protected]>
Co-authored-by: Sam Bull <[email protected]>

Author: veeceey

CHANGES/1299.bugfix.rst

@@ -0,0 +1,2 @@
+Fixed broken RST markup in ``items()`` docstrings
+-- by :user:`veeceey`.

multidict/_multidict_py.py

@@ -720,7 +720,7 @@ def keys(self) -> KeysView[str]:
         return _KeysView(self)
 
     def items(self) -> ItemsView[str, _V]:
-        """Return a new view of the dictionary's items *(key, value) pairs)."""
+        """Return a new view of the dictionary's items as ``(key, value)`` pairs."""
         return _ItemsView(self)
 
     def values(self) -> _ValuesView[_V]:
@@ -1194,7 +1194,7 @@ def keys(self) -> KeysView[str]:
         return self._md.keys()
 
     def items(self) -> ItemsView[str, _V]:
-        """Return a new view of the dictionary's items *(key, value) pairs)."""
+        """Return a new view of the dictionary's items as ``(key, value)`` pairs."""
         return self._md.items()
 
     def values(self) -> _ValuesView[_V]: