gh-151950: Fix dangling reference in pickletools docs

Author: BHUVANSH855

Doc/library/pickletools.rst

@@ -108,7 +108,7 @@ Programmatic interface
 
    Provides an :term:`iterator` over all of the opcodes in a pickle, returning a
    sequence of ``(opcode, arg, pos)`` triples.  *opcode* is an instance of an
-   :class:`OpcodeInfo` class; *arg* is the decoded value, as a Python object, of
+   :class:`!OpcodeInfo` class; *arg* is the decoded value, as a Python object, of
    the opcode's argument; *pos* is the position at which this opcode is located.
    *pickle* can be a string or a file-like object.