Fix openocd command in Verify Installation section.

[airelil]

For the recent STM32F303VCT6, it should refer interface/stlink-v2-1.cfg.
Same as in https://github.com/rust-embedded/cortex-m-quickstart/blob/be44af69cc91e2ff5b75f400e09488cba44e9f59/openocd.cfg#L7
Otherwise, using the currently specified interface/stlink.cfg produces openocd error:

Error: open failed
in procedure 'init'
in procedure 'ocd_bouncer'

[rust-highfive]

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[adamgreig]

Thanks for this PR! I think this is related to #263. In the latest version of openocd, you should use the new stlink.cfg, which works for all ST-links. However, in openocd 0.10, which is the most recent released version (albeit a few years old), there are still the -v2 etc scripts.

Perhaps the book should be updated to suggest trying out the -v2, especially since lots of people are hitting this issue, but it's not right to only suggest it, since users on the latest versions of openocd (and users in the future) will need what's currently in the book.

[airelil]

Fair enough. Thank's for pointing me to #268. It's just from a consistency point of view, openocd version 0.10 is still what user ends up with by following the installation instructions for Linux. Will it be a different version on Mac or Windows platform? Notice also that ver 0.10 is presented in the example of expected output from openocd and st*v2 scripts are referred from openocd.cfg coming with the "cortex-m-quickstart" template recommended by the book in the next section.