Vote for the approval of RFC 8

https://github.com/polkadot-fellows/RFCs/pull/8

Introduce a new member.

- `origin`: Must be the `AdminOrigin`.
- `who`: Account of non-member which will become a member.
- `rank`: The rank to give the new member.

Weight: `O(1)`

- Problem Statement: Lack of approval for RFC 8 by the Polkassembly Fellowship community.
- Significance: Ensuring community input and consensus on RFC proposals.
- Proposed Solution: Vote for the approval of RFC 8.
- Expected Outcomes: Increased community engagement and decision-making in the Polkassembly Fellowship.

#27 Approval of RFC 8