Posters: Add Python Editor poster from the Foundation.

[carlosperate]

Resource description

Python Editor poster - A poster of the micro:bit Python Editor illustrating its features.

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• I have read and understood the Contribution Guidelines
• I am making an individual pull request for each suggestion
• I have used the correct spelling and capitalisation for BBC micro:bit, micro:bit, and Micro:bit Educational Foundation (resource title could be excluded if there is a good reason)
• The content linked is in English, or it contains an English translation
• I have added the new entry to the bottom of its the category
• I have used the following format:

- [Resource Title](link) - Resource short Description (2 lines or less in total)