Add JSONEncode supporting buffers

[metatablecat]

Changes

Adds a previously undocumented note about buffer being supported in JSONEncode, which returns a compressed and encoded variant of the buffer.

I'm unsure if Base64 in this addition is formatted correctly to style.

Checks

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[IgnisRBX]

Do you mean a buffer created through the buffer library, such as through buffer.create()?
https://create.roblox.com/docs/en-us/reference/engine/libraries/buffer#create

[aetter]

Hey @metatablecat, this is super interesting, thanks for bringing it to our attention. A couple things:

• We don't take PRs on the reference documentation anymore, but I'll port a version of this over to our internal source. It typically takes a couple weeks to get reviewed and incorporated into a release.
• My extremely quick testing indicates that JSONEncode() doesn't always compress the buffer (fromstring seems to come out as base64 rather than zbase64), so I'll work with engineering to see if there's a bit more complexity to note about how these get handled.

[metatablecat]

Hey @metatablecat, this is super interesting, thanks for bringing it to our attention. A couple things:

* We don't take PRs on the reference documentation anymore, but I'll port a version of this over to our internal source. It typically takes a couple weeks to get reviewed and incorporated into a release.

* My extremely quick testing indicates that JSONEncode() doesn't always compress the buffer (`fromstring` seems to come out as `base64` rather than `zbase64`), so I'll work with engineering to see if there's a bit more complexity to note about how these get handled.

I know this was closed a week ago but I wanted to give this a little more investigating myself, it appears it only generates zbase64 if the stream could actually be compressed, I don’t know what specifically zstd does to consider if a stream is "compressible" but it is what it is.

[aetter]

Hey @metatablecat, this is super interesting, thanks for bringing it to our attention. A couple things:

* We don't take PRs on the reference documentation anymore, but I'll port a version of this over to our internal source. It typically takes a couple weeks to get reviewed and incorporated into a release.

* My extremely quick testing indicates that JSONEncode() doesn't always compress the buffer (`fromstring` seems to come out as `base64` rather than `zbase64`), so I'll work with engineering to see if there's a bit more complexity to note about how these get handled.

I know this was closed a week ago but I wanted to give this a little more investigating myself, it appears it only generates zbase64 if the stream could actually be compressed, I don’t know what specifically zstd does to consider if a stream is "compressible" but it is what it is.

100%. I believe I went with "it encodes to base64 (and often compresses)" since the cases aren't obvious and we handle it with JSONDecode regardless.