Add warning to docs that supabase-js doesn't support fire-and-forget

[JeongJuhyeon]

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Not sure where best location would be

Describe the problem

For most who have done async calls Typescript or Javascript, it's common to sometimes "fire and forget" (i.e. not await the promise) for async calls where they don't care about the result. This doesn't work with supabase-js, the query will not be executed. From a technical perspective it makes sense since it's a query builder, but many people have never used one and have only used async calls with libraries that directly make http requests or execute db statements.

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