Include install instruction for downloading from the "releases" page

[andrewkww]

In the README file and the install page: https://www.sidefx.com/tutorials/game-dev-toolset-installation/
it tells the user to download the through the "Clone or download" button. While this gives the cutting edge version, the HDAs are also in the unpacked format. This might not be best for production environments. It'd be good to also mention that the tool can be downloaded from the "releases" page, where the HDAs are packed, and probably more suitable for production.

Maybe for those who want to download the cutting edge version, also include a quick instruction to pack the HDA files?