Updates to the Getting Started Guide:
* Update title to simply be "Getting Started Guide"
* Simplify and remove instructions that are redundant
* Add a note explaining the difference between 'nuc11tnbi5' and
'nuc11tnhi5'
Tracked-On: #6225
Signed-off-by: Geoffroy Van Cutsem <geoffroy.vancutsem@intel.com>
