README: dfu-utils -> dfu-util, cosmetic

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extra : source : 700b7f53650156f8b927f1dbaabe14261e4ecad3
Merge pull request #397 from hg42/fix-readme-dfu-util

README: dfu-utils -> dfu-util, cosmetic
Merge remote-tracking branch 'upstream/edge' into edge
Update to latest binary
Merge remote-tracking branch 'upstream/edge' into edge