Update MAINTENANCE.md

[bracevac]

Update the topic areas and responsible internal team members

[Gedochao]

LGTM

[hamzaremmal]

We don't have the issue supervisor role anymore... (See the begining of the document)

[bracevac]

We don't have the issue supervisor role anymore... (See the begining of the document)

Do we want to get rid of that @Gedochao ?

[Gedochao]

We don't have the issue supervisor role anymore... (See the begining of the document)

Do we want to get rid of that @Gedochao ?

Sure. Either here, or a subsequent PR.
Technically, the issue supervisor's part is still there in a way, as it got merged into the Product Manager role.
As in, I guess we can just mention it's me doing it.

[hamzaremmal]

Technically, the issue supervisor's part is still there in a way, as it got merged into the Product Manager role

But all of this is outdated

https://github.com/scala/scala3/blob/main/MAINTENANCE.md?plain=1#L27-L62