Fixed import typo: with_job is located in root flow module (#158)

* Fixed import typo: with_job is located in root flow module

* [pre-commit.ci] auto fixes from pre-commit.com hooks

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Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

docs/source/flow-project.rst

@@ -177,9 +177,11 @@ If we implemented and integrated the operation and condition functions correctly
 
     .. code-block:: python
 
+        from flow import with_job
+
         @MyProject.operation
         @MyProject.post(greeted)
-        @MyProject.with_job
+        @with_job
         def hello(job):
             with open('hello.txt', 'w') as file:
                 file.write('world!\n')