Update src/utils/variable_manipulations.jl

Co-authored-by: Tapio Schneider <tapio@caltech.edu>

Author: charleskawczynski

src/utils/variable_manipulations.jl

@@ -85,7 +85,7 @@ the current tracer is `ρq_tot` (to allow for special handling).
 
 Arguments:
 
-- `f`: A function to apply to each scalar. It must have the signature `f
+- `f`: A function to apply to each grid-scale scalar. It must have the signature `f
   (ᶜρχₜ, ᶜρχ, ρχ_name)`, where `ᶜρχₜ` is the tendency field, `ᶜρχ`
   is the state field, and `ρχ_name` is a `MatrixFields.@name` object.
 - `Yₜ`: The tendency state vector.