Tutorial tweaks

[baconpaul]

Formula tutorial notes from j5v

# 07 Example
- Doesn't modulate anything. Might help to hear it.
- Typo line 21 "ever" -> "every"
# All examples
- Maybe longer or more descriptive modstate property names and local variable names?
- There are some Lua aspects that might not be self-documenting, like implicit tertiary assignments using `condition and trueValue or falseValue`, and # for array length. We don't want to document Lua, but I expect a proportion of our uninititated users might not find this intuitive.
- Style crit (and I'm being picky!): maybe rewrite informal stuff. e.g. 08:11
> just read the values as - well - values.
could be
> just allow the controls to be used as value inputs.

[baconpaul]

rename modulators also