fix: update teams in readme

[wesleytodd]

I updated the teams here to do the following:

1. Updated the team membership to reflect the lists in the readme (removed @ruddermann, but we will always welcome you back if you want 😄)
2. @expressjs/security-wg-captains now exists and has maintain permissions on this repo and the triage repo
3. @expressjs/security-wg is now the parent for both @expressjs/security-wg-captains and @expressjs/security-triage

Added the team tags to the readme to aid in folks knowing which one to use for what.

[ctcpip]

nit: typically working groups have 'chairs'

[ctcpip]

lgtm, but would prefer if we used the word 'chairs' for WG leads

[wesleytodd]

nit: typically working groups have 'chairs'

Valid, but since we have a specific role and defined capabilities for that role that match to what we need, I used Captain. This was more of a pragmatic thing.

[wesleytodd]

Specifically this: https://github.com/expressjs/discussions/blob/master/docs/GOVERNANCE.md#project-captains

[ctcpip]

actually I think that's even more reason to not overload the term! not dying on this hill though 😊

[wesleytodd]

Hm, I am not overloading it. It is literally exactly what is documented there. These people get membership on the team which has maintain and should have the same exact process for nominations. That is intentional IMO.

[ctcpip]

should have the same exact process for nominations

they're not currently the same, nor should they be, but that's also a separate issue 😊