Arabic translation for how to contribute

[aseel-aaa]

• Have you followed the contributing guidelines?
• Have you explained what your changes do, and why they add value to the Guides?

Please note: we will close your PR without comment if you do not check the boxes above and provide ALL requested information.

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[aseel-aaa]

Hi @jmeridth
I added translation for (how to contribute) article. But what I should do here with these tests

((* At _site/ar/how-to-contribute/index.html:1003:

internally linking to #a-checklist-before-you-contribute; the file exists, but the hash 'a-checklist-before-you-contribute' does not))