[5.2] update README

[heelc29]

Summary of Changes

• J5.2 is no longer under heavy development
• information about node/npm version was not upmerged from 4.4-dev [4.4] Node 20 #42331

Testing Instructions

code review

Link to documentations

Please select:

• No documentation changes for docs.joomla.org needed
• No documentation changes for manual.joomla.org needed

[alikon]

I have tested this item ✅ successfully on e0a09cb

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[Quy]

I have tested this item ✅ successfully on e0a09cb

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_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/44312.}

[Quy]

RTC

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[pe7er]

Thanks @heelc29 !