Update the contributing.md to match the new beginners guide

[dmanners]

Description (*)

The aim of this pull request is to update the following files to make them more useful to people.

• contributing.md
• issue_template.md
• pull_request_template.md

Questions and thoughts

• Should the contributing.md have more information from the beginners guides or is it ok just to link in but leave the information as is?
• After a bit of feedback and usage I can see that the issue and pull request templates are not too clear. I have removed some lines that I think are not needed and also added a new section for open questions as a few people have asked if it was ok to ask question on a PR you are writing.

I would be happy for any further thoughts or input on these changes.

[m2-assistant]

Hi @dmanners. Thank you for your contribution
Here is some useful tips how you can test your changes using Magento test environment.
Add the comment under your pull request to deploy test or vanilla Magento instance:

• @magento-engcom-team give me test instance - deploy test instance based on PR changes
• @magento-engcom-team give me 2.3-develop instance - deploy vanilla Magento instance

For more details, please, review the Magento Contributor Assistant documentation

[magento-engcom-team]

Hi @okorshenko, thank you for the review.
ENGCOM-5137 has been created to process this Pull Request

[VasylShvorak]

Notice: QA not applicable

[m2-assistant]

Hi @dmanners, thank you for your contribution!
Please, complete Contribution Survey, it will take less than a minute.
Your feedback will help us to improve contribution process.