Add snap installation instructions to the README

[brlin-tw]

Currently, the gotop-brlin snap name is used, should be replaced after the snap name issue is settled.

Signed-off-by: 林博仁(Buo-ren Lin) Buo.Ren.Lin@gmail.com

[cjbassi]

One question: I installed the package and it works for me, but I didn't have to run any of the snap connect commands (running snapd on Arch Linux). Were those commands necessary for you?

[brlin-tw]

The following is the screenshot without connecting anything with the original Ubuntu kernel:

Note the missing data in the disk usage and temperature widgets, these are due to the missing connection to the mount-observe and the hardware-observe interfaces. As the Arch linux kernel doesn't support full Snapd sandboxing features it is possible that some data is accessible even when the interface isn't connected, you can check out the sandboxing feature support status by running the snap debug sandbox-features command in a terminal.

Comparison after connecting to the 2 aforementioned interfaces:

I'm not sure about the effectiveness of connecting the system-observe interface though, it might be unnecessary at all, I'll check if it can be dropped.

Most of the interface connecting instructions may be dropped after requesting auto-connection for those interfaces at the Snap Store's end, refer Process for aliases, auto-connections and tracks - doc - snapcraft.io for more details.

[cjbassi]

I went ahead and updated the readme with the snap instructions. If you find any information about the permissions, then feel free to post it at #119. Thanks again!