Docs: Fix incorrect sphinx markup for a class member (pythonGH-130970)

(cherry picked from commit 9a634c5)

Co-authored-by: Yuki Kobayashi <[email protected]>

Author: koyuki7w

Doc/library/dis.rst

@@ -492,7 +492,7 @@ details of bytecode instructions as :class:`Instruction` instances:
       :class:`dis.Positions` object holding the
       start and end locations that are covered by this instruction.
 
-   .. data::cache_info
+   .. data:: cache_info
 
       Information about the cache entries of this instruction, as
       triplets of the form ``(name, size, data)``, where the ``name``