suggestion: expand readme/state diagram

[devriesewouter89]

Hi I've just tested this balenablock. I wasn't entirely sure how the connection flow worked, for a project I first need to prepare some devices in a research context and have them sent over to test persons where these persons need to connect the device to their local network. These test persons are not tech savy (up to the point that we don't want to ask them to use an ethernet cable), yet the block would make it possible via a decent project tutorial. From that perspective, I wasn't sure by reading the documentation that:

1. It is necessary for WifiConnect to be downloaded initially to the SD card (which is logically of course)
2. If you download an image from balena dashboard, it doesn't hurt the wificonnect flow to have it connected to an initial Wifi network (option when choosing to download an image: ethernet + Wifi). This makes it easier to get a headstart: flash a few images in parallel and have them download their initial image over wifi, then have the devices sent over to test persons who can use the WifiConnect container.
3. The state diagram/readme doesn't show what happens when a connection is made once, yet the SSID can't be found anymore (say someone changes his/her SSID or moves a device). Apparently/luckily the block sets up the hotspot again after a reboot (not after a while). Nice block btw!