[5.3] contributing.md

[brianteeman]

Updates branch information

Link to documentations

Please select:

• Documentation link for docs.joomla.org:

• No documentation changes for docs.joomla.org needed

• Pull Request link for manual.joomla.org:

• No documentation changes for manual.joomla.org needed

[tecpromotion]

Looks right.

[QuyTon]

I have tested this item ✅ successfully on a15a089

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[tecpromotion]

I have tested this item ✅ successfully on 9413706

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_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/45883.}

[tecpromotion]

RTC

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_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/45883.}

[rdeutz]

Thanks