Is your concern that: These days, LEDE development is in flux. We should warn people that the packages available on a particular day might not work with an image retrieved the day before.
(Not sure how to quote you)
Development is always in flux, but yes I am suggesting we be clear, focused on new users, that the repository changes frequently (generally every 1-3 days) and that it's important, if they want to add functionality, that they also save the matching (400MB or so) packages at the same time. I don;t think it can hurt to make a statement about trunk, even if already made elsewhere, that trunk may be more buggy and does not include LuCi, etc.
We do not have a "Stable" release, but as I read the instructions, I feel that they are focused on a stable release. For new devices, the latest release may be trunk (there are a few DD Trunk in the OpenWrt TOH). It may be 6-12 months until they are in the next stable release.
NOTE - Currently for all platforms there is (For new devices there may be) no stable release. We run buildbots frequently to update trunk with the latest firmware and packages. Many of these packages need to match the appropriate level of firmware. If the latest release for your device is "trunk" and you want to enhance the capabilities of your device with packages, you should download both the target and instruction set packages to your local environment when you download your firmware. See this note on how to save the files and options on how to load them to your device. See this note for the differences between a stable release and trunk release.
Notes not included, but I expect include wget use, how to load individual packages to the deicev (WinSCP or FTP, etc) and how to update the pointers to the available repository on ones lan or attached USB device, etc.
As the saying goes: Make it idiot proof and someone will build a better idiot.