Consistent styling of architecture type (8-bit)

[avivace]

There are some different letter styling around the document:

• 8 bit
• 8 bit
• 8-bit
• 8bit

[aaaaaa123456789]

"8 bits" and "8-bit" have different usages in the English language. The former is used when talking about the quantity ("a byte has 8 bits"), while the latter is used as an adjective ("8-bit bytes are nowadays standard"). "8bit" is obviously wrong, and "8 bit" is likewise incorrect.