Include url to device wiki page in deviceinfo

IMO, it would be useful to link each device page in the devices page from their deviceinfo.

For example, for asus-grouper:

# Reference: <https://postmarketos.org/deviceinfo>
# Please use double quotes only. You can source this file in shell scripts.
# Wiki: <https://github.com/postmarketOS/pmbootstrap/wiki/asus-grouper-%28Google-Nexus-7-2012%29>
...

What do you think? We can also beautify the urls with aliases like postmarketos.org/devices/grouper

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