Update manual download section to add GitHub Actions and update Cirrus CI section.

[Daeraxa]

Updates the manual download section which previously only detailed how to download binaries from Cirrus CI.

• Adds a new GitHub Actions section and links to the pulsar-rolling-releases repo (as only people with read access to the main repo can download artifacts directly)
• Added section to explain what is produced on GHA vs Cirrus
• Updated a few areas to clarify things (like adding in architectures for binaries where they are distinct - previously this wasn't needed for Cirrus as architecture was selected before the binary).

[confused-Techie]

While this overall looks great, would it make any sense to mention the download microservice here? Such as listing how to use the pulsar-rolling-release repo, then add on, but if you don't want to look manually you can use the download microservice? Just sense it also solves the problem of having to find a release with the right binaries

[Daeraxa]

Well this is part of the whole Download page so to get to this bit one would have already gone past the explanation of the rolling releases and all the links to them, this section is very much buried at the bottom specifically for downloading manually despite all the previous instructions and links to make life easy.

[confused-Techie]

Sorry I didn't get to this one sooner after the initial review.

Looks good and lets get this one merged!

[Daeraxa]

Honestly I forgot about this, can I quickly get a fact check on:

• Cirrus CI is only used for building Apple silicon (macOS M1/M2) and ARM
  Linux binaries. These are run less frequently (every other day).

I can't remember if that is true or not

[confused-Techie]

@Daeraxa Very nearly. For all intents and purposes it's true, although technically it's not built every other day. It's Monday, Wednesday and Friday at 3PM.

So if you want to change that feel free

[Daeraxa]

Thanks, I think it is best for it to be factually correct.

[confused-Techie]

LGTM! And to make sure we don't forget again, I'll go ahead and merge this one