Various improvement suggestions

[meithecatte]

Feel free to cherry-pick these.

• Justify the text
• Typo fixes
  • arithmeticas -> arithmetics
  • alternate notation -> alternative notation
  • operiton -> operation
• Modify the registers part to not say that flags are general-purpose
• Clarify that the CF, ZF notation will not work when referring to flags the source code.
• Describe ldh, dw and dl where first mentioned
• Turn the hexadecimal to binary table into an actual table
• Remove an "IIRC" about inc sp and dec sp - I've checked, it's correct

[ISSOtm]

Imo these all make sense. Let's do this--