Adds example static validator

Updates doc string to show example usage.

examples/validation/static_validator/README.md

@@ -0,0 +1,24 @@
+# Example showing graph validation
+
+This uses the StaticValidator class to validate a graph.
+
+This specifically show how, for example, you can validate tags on functions.
+
+ - run.py shows the validator and how to wire it in
+ - good_module.py shows a node with the correct tags
+ - bad_module.py shows a node with the wrong tags
+ - notebook.ipynb shows how to run the same code in a notebook
+
+To run the example, run `python run.py` and you should see the following output:
+
+```
+# good_module.py ran
+{'foo': 'Hello, world!'}
+
+# bad_module.py didn't have the right tags so graph building errored out
+...
+Hamilton.lifecycle.base.ValidationException: Node validation failed! 1 errors encountered:
+  foo: Node bad_module.foo is an output node, but does not have a table_name tag.
+```
+
+Alternatively you can run this all via the notebook.ipynb.

examples/validation/static_validator/bad_module.py

@@ -0,0 +1,6 @@
+from hamilton.function_modifiers import tag
+
+
+@tag(node_type="output")
+def foo() -> str:
+    return "Hello, world!"

examples/validation/static_validator/good_module.py

@@ -0,0 +1,6 @@
+from hamilton.function_modifiers import tag
+
+
+@tag(node_type="output", table_name="my_table")
+def foo() -> str:
+    return "Hello, world!"