Phase out specific hardware recommendations

[nathandyer]

Right now, we're recommending a handful of specific models of laptops for use with Qubes and SecureDrop Workstation (currently all ThinkPads).

Given the maintenance burden, we should consider removing specific recommendations in favor of pointing users to the Qubes Hardware Compatibility List (HCL): www.qubes-os.org/hcl/

[zenmonkeykstop]

As per comments in #224 and elsewhere - the Qubes HCL may be a bit difficult to navigate for folks looking for a simple yes/no purchasing decision, and as a community resource it's not reasonable to expect it to be exhaustive or always up-to-date.

Proposing instead:

• First recco is for qubes-certified hardware, as there are now several providers
• Second recco is for our dev team's most recent SDW dev hardware, as we can commit to some level of testing here
• Third recco is the HCL, with strict provisos that we recommend it only for people looking to re-use existing h/w and that they would still need to do a full BIOS update and test Qubes install.