Material API what's new

[adrien-de-tocqueville]

Purpose of this PR

add section in what's new for #5761

Also add what's new for main light node #5086

[github-actions]

Hi! This comment will help you figure out which jobs to run before merging your PR. The suggestions are dynamic based on what files you have changed.
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/jobDefinition/.yamato%2Fall-hdrp.yml%23PR_HDRP_trunk
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/jobDefinition/.yamato%252Fall-shadergraph.yml%2523PR_ShaderGraph_trunk
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[github-actions]

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[sebastienlagarde]

@adrien-de-tocqueville guess you will need to create a Jira task?

[Vic-Cooper]

Added re-write suggestions in comments. Changed the order of information to make the new feature more clear :)

[adrien-de-tocqueville]

i forgot to add the new node to the table of content for shadergraph doc. So i did it in this PR

[sebastienlagarde]

Feedback adressed, merging