[Eclipse] Vulnerability Reports no longer accepted by email

[danielpeintner]

I think updates to SECURITY.md are needed.

I got the following email, see https://www.eclipse.org/lists/eclipse.org-committers/msg01582.html

[egekorkan]

@danielpeintner could you update first https://github.com/eclipse-thingweb/.github/blob/main/SECURITY.md and then we copy paste it everywhere.

[danielpeintner]

see eclipse-thingweb/.github#11