DOC: Fix typo of =! to != in docstring (#36077)

This fixes GH36075.

Author: daytonb

pandas/core/ops/docstrings.py

@@ -611,7 +611,7 @@ def _make_flex_doc(op_name, typ):
 Among flexible wrappers (`eq`, `ne`, `le`, `lt`, `ge`, `gt`) to comparison
 operators.
 
-Equivalent to `==`, `=!`, `<=`, `<`, `>=`, `>` with support to choose axis
+Equivalent to `==`, `!=`, `<=`, `<`, `>=`, `>` with support to choose axis
 (rows or columns) and level for comparison.
 
 Parameters