Fix: remove extra character in `rooms.md`

[agrattan0820]

Hi! Just noticed that there was an extra quotation mark character before sids in the docs

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Name	Status	Preview	Comments	Updated (UTC)
socket-io-website	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Jun 17, 2023 8:49pm

[darrachequesne]

Good catch, thanks :+1: