fix(curriculum): add 'should' to correct typo in step 68 (freeCodeCamp#61916)

Co-authored-by: Tiffany Grevious <tjgrevious@example.com>

Author: DevchamploO

curriculum/challenges/english/07-scientific-computing-with-python/learn-special-methods-by-building-a-vector-space/66019258a7c71d4ae50da42e.md

@@ -25,7 +25,7 @@ Your `__le__` method should have two parameters, `self` and `other`.
 ({ test: () => assert(runPython(`_Node(_code).find_class("R2Vector").find_function("__le__").has_args("self, other")`)) })
 ```
 
-Your `__le__` method return the opposite of `self > other`.
+Your `__le__` method should return the opposite of `self > other`.
 
 ```js
 ({ test: () => assert(runPython(`_Node(_code).find_class("R2Vector").find_function("__le__").has_return("not self > other")`)) })