Update overview.md

[Poryg1]

I aim to make the "type switches" section clearer to a newbie.

As it stands: Variable 'v' changes types in a messy way: 'union' chapter uses: 'v := Value' 'type switches' then uses: 'value := Value' and 'switch v in value'. Then in the #no-nil tag, the v jumps back to "v := Value". In two instances, 'v' is an instance of Value. In the third one, it's not an instance of Value, but actually value of an instance of Value. The type discrepancy can be confusing, so I unified the types.

It's also not 100% clear what exactly the "v" even is in the type switches section. The description spoke about "types, not values", which may make it look like "v" is a type representation when it's actually value. So I:

• specified in the description that the switch searches for types of a value, not just types
• used a more descriptive "val" name instead of "v"
• replaced one of the asserts with a fmt.println. Assert is a compile time instruction and provides no useful information here. If I was to copy paste the code to learn from it, I receive no visual feedback. fmt.println will give immediate visual feedback on what exactly "val" means when it is a string.

[gingerBill]

All you have done is changed the name of variable and changed text in parentheses into a subclause.

This does not clear anything up whatsoever.