Fix grammar and typo in documentation

- README.md: Fix broken sentence "These methods function a submodel" ->
  "These methods construct a submodel via a projection"
- README.md: Fix "approximation information" -> "approximate information"
- src/utils.jl: Fix typo in docstring "Returns true is" -> "Returns true if"

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: ChrisRackauckas

README.md

@@ -11,8 +11,8 @@
 
 ModelOrderReduction.jl is a package for automatically reducing the computational complexity
 of mathematical models, while keeping expected fidelity within a controlled error bound.
-These methods function a submodel with a projection
-where solving the smaller model gives approximation information about the full model.
+These methods construct a submodel via a projection
+where solving the smaller model gives approximate information about the full model.
 MOR.jl uses [ModelingToolkit.jl](https://docs.sciml.ai/ModelingToolkit/stable/)
 as a system description and automatically transforms equations
 to the subform, defining the observables to automatically lazily reconstruct the full

src/utils.jl

@@ -28,7 +28,7 @@ end
 """
 $(SIGNATURES)
 
-Returns `true` is `expr` contains variables in `dvs` only and does not contain `iv`.
+Returns `true` if `expr` contains variables in `dvs` only and does not contain `iv`.
 
 """
 function only_dvs(expr, dvs, iv)