Update units-of-iota.md

[Schnurzle]

corrected the naming of the units

Description of change

Please write a summary of your changes and why you made them. Be sure to reference any related issues by adding fixes # (issue). the naming of the units was wrong.

Type of change

Choose a type of change, and delete any options that are not relevant.

• Bug fix (a non-breaking change which fixes an issue)

Change checklist

Add an x to the boxes that are relevant to your changes, and delete any items that are not.

• [x] I have followed the contribution guidelines for this project
• [x] I have performed a self-review of my changes