Add multilingual Agila learning examples and Git practice guide

en/ada-contracts-and-review/README.md

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+# A reviewed progress component
+
+Extend the level component with a clearly specified operation of your own. Submit both successful and expected-failure evidence plus a reviewable explanation.
+
+- Record the allowed inputs and promised result.
+- Keep assertion checking enabled and record compiler settings.
+- Test low and high valid inputs and one precondition violation separately.
+- Demonstrate that a deliberately wrong body is caught, then restore it.
+- Explain a remaining limitation and identify one next learning step.