Improved ligability for hardware.md

[tomasApo]

When following Section 2.2 Hardware, I would get stuck trying to launch gdp but wouldn't get stuck in section 2.1 QEMU. There is a disparity between the two sections of code even though they achieving the same function. My suggestion is to warn the user about the different versions of gdp vs gdb-multiarch in the same fashion as the QEMU section.

[rust-highfive]

r? @jamesmunns

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[bors[bot]]

Build succeeded:

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