Update Question 18.11:

• Add non-breakable spaces for better rendering
• Unfold and mark up Microsoft, Intel
• Mark up literals with <literal>
• Fix formulas, add <superscript>
• Fix grammar (suggested by gabor)
• Remove Ethernet address as example, because it is 48 bits long
• Reword sentences with grammar bogons (submitted by trhodes)

Reviewed by: trhodes
Approved by: gabor